Today, flat window glass is a cheap mass-produced material given little consideration, but in the past window glazing was a highly taxed status symbol.
Nothing has influenced sash window design more than the history of glass production. After all, the primary purpose of a window is to mount and protect the delicate glass.
When handmade glass could only be produced in small panes, windows were made with many glazing bars to increase the glazed area. As glassworks managed to produce larger sheets the windows grew in size and glazing bars became only a decorative element.
This article focuses on the development of flat glass production in Britain but is also relevant to the heritage of all former British colonies. For example; Until the 1930’s all Australian glass was imported from the UK, Belgium or to a lesser extent America.
“The use of glass in our windows, instead of the louvre-boards of our ancestors, has introduced comfort into the meanest dwelling which previously did not belong to the richest palace. By means of this contrivance the light is filtered from the wind, the rain, and the cold; we can enjoy the one without being inconvenienced by the others; and we can, in conjunction with our methods of warming, create an in-door climate adapted to our feelings and desires” Charles Tomlinson 1854
Table of Contents
How Taxation Influenced Windows
For many years in England, both windows and the glass in them were taxed individually. This taxation directly influenced the number of windows being used in dwellings, as well as influencing glassworks towards making thinner sheets of glass.
The Window Tax 1696 — 1851
A tax on “light and air.”
Before income taxes, the number of windows in a persons home was used as a measure of wealth. When introduced the window tax was charged annually at 2 shillings for less than 10 windows, 4 shillings for 10-20 windows and 8 shillings for 20 windows or more. Sometimes even a room vent might be counted as a window, in an attempt to extract more of this unpopular tax on light and air.
Whilst many windows were inevitably bricked up to reduce taxation, not every bricked up window was done for this reason. Georgian architecture, in particular, incorporated “blind windows” in order to preserve the symmetry of the facade. Blind windows were purposely built ‘bricked up’ to suit interior floor plans. Later as the Victorians constructed the underground rail network, some streets had a false frontage with bricked doors and windows. 23 – 24 Leinster Gardens, Queensway, West London are mock houses built entirely of brick, with painted-on windows and doors.
By the time the tax was abolished in 1851, it was effectively preventing 9 out of 10 homes in the country from having more than seven windows.
Whilst the term “daylight robbery” is commonly linked to the window tax, many etymologists believe the connection to be a myth.
The adage ‘free as air’ has become obsolete by Act of Parliament. Neither air nor light have been free since the imposition of the window-tax. We are obliged to pay for what nature lavishly supplies to all, at so much per window per year; and the poor who cannot afford the expense are stinted in two of the most urgent necessities of life.…[Charles Dickens, 1850]
The Glass Tax 1745 — 1845
The glass excise tax was levied on all glass products and calculated by weight. Clear glass such as plate and crown window glass were taxed at the highest rate, whilst coloured brown and green bottles were taxed less. Thinner, lighter crown window glass became dominant as a means to reduce the tax burden.
In a hygienic point of view, the enormous tax on glass, amounting to more than three hundred per cent on its value, is one of the most cruel a Government could inflict on the nation … The deficiency of light in town habitations, in a great measure caused by the enormous cost of glass, is universally admitted to be one of the principal causes of the unhealthiness of cities …[The Lancet 1845]
In 1845, the restriction that only allowed glasshouses to make either flint or crown glass, but not both, was lifted.
Glass is made from the process of heating sand to an extremely high temperature until it turns into a malleable liquid.
Soda–lime-silica glass is used for windowpanes and mostly composed of white silica sand, with a carbonate ‘Soda” (saltcake) flux added to reduce the high melting point of the silica sand, from about 1600 degrees to 750 degrees. Some limestone is also added as a stabiliser to stop the finished glass from dissolving in water. Recycled broken glass, known as ‘cullet’ might be also be added to the mix. The resultant molten glass mix is called ‘metal’ by glass workers.
Annealing is the process of slowly cooling the hot glass. Inadequately annealed glass is likely to crack or shatter, even spontaneously!
Whilst early glass use dates back to ancient Egypt or earlier, the first real evidence for window glass comes from the Romans. Pompeii has examples of rough cast translucent glass placed in stonework openings. Later the Romans became accomplished glassworkers producing coloured as well as ‘aqua’ and true colourless glasses. The basic glass blowing and casting methods used by the Romans formed the basis of all glass production until the 20th century.
“You’ve likely heard the superstition that breaking a mirror causes seven years of bad luck? The Romans actually started that superstition as a scare tactic to discourage carelessness around mirrors. At that time, mirrors were extremely expensive and fragile. The silver backing cost was the least of the expense, as the glass production took much more time and effort.” Study.com
From the late eighteenth century, glassworks buildings comprised large ‘glass cones’ with a large central chimney that served two or more furnaces. As production moved to sheet glass the buildings grew to become large industrial factories located close to high-quality sand and coal supplies as well as good transportation networks.
Finished glass would be inspected for flaws and graded before sale. It was sold as either best, seconds, thirds or fourths with thirds being the average window glass. Fourths may be used on the rear of buildings, seconds could be used for high quality work and firsts would be used for picture frames and ‘looking glass’ mirrors.
Glass Flow – It is a myth that glass is a liquid that can sag downward over time. The truth is that once solidified, glass stops flowing. The reason old glass is thicker at the bottom is that handmade glass is of uneven thickness. The thicker and heavier edge of the pane would routinely be placed at the bottom for stability, with the convex face outwards, by the glazier. The ‘sagging’ of the glass surface is only a result of production methods and not a sign of flowing over time.
“Flattened sheet glass and patent plate should be cut with the convex side of the air bubbles downwards or it will be liable to crack starwise and it should be glazed with the convex face outwards or it will present the appearance of being hammered on the face”Seddon
At a molecular level glass is not truly a solid or a fluid but it can be thought of as ‘glass’, a state somewhere between the two; still it would take longer than the age of the Universe for the glass to sag appreciably.
In AD674 french glassmakers were invited to the North East of England to make church stained glass. It is presumed that local people copied their skills, as for almost two hundred years the North-East became the home of early English glass production.
For a long time, the glass produced in mainland Europe was far more advanced than in Britain. European craftsmen closely guarded their techniques and restricted access to a more pure form of soda, made from the ashes of the coastal ‘Barilla’ plant.
Flat glass was imported into Britain until Venetian and French glassmakers started to migrate to England in the 1560s, forming a small British industry. From 1685 and in 1688 protestant Huguenots were driven out of France, bringing a new influx of skilled tradesmen to Britain. Eventually the new production methods these migrants introduced combined with British ingenuity, during the industrial revolution, to bring us today’s mass-produced high-quality glass.
The largest producers of hand-made glass in 19th Century England were Pilkington Brothers of St Helens, Hartleys of Sunderland and Chance Brothers of Birmingham. These were the only firms already making sheet glass at the time the glass tax was abolished and they drove the longer-established crown glass producers out of business. Pilkington Brothers went on to become the leading producer of architectural glass worldwide.
By 1860 Pilkingtons and Chance Brothers were operating nine furnaces each, and Hartleys six. Between them, these three glassmaking firms were producing 75% of all the window glass made in England.
A window glass production technique dating to the Romans. A small glass cylinder, the ‘muff’ or ‘muffin’, was blown using a blowpipe, sliced lengthwise and unrolled into a flat piece.
“Glass windowpanes were first made in the early imperial period, and used most prominently in the public baths to prevent drafts. Because window glass in Rome was intended to provide insulation and security, rather than illumination or as a way of viewing the world outside, little, if any, attention was paid to making it perfectly transparent or of even thickness. Window glass could be either cast or blown. Cast panes were poured and rolled over flat, usually wooden molds laden with a layer of sand, and then ground or polished on one side. Blown panes were created by cutting and flattening a long cylinder of blown glass.” The Met
This late medieval glass was produced using river sand and wood ash. Impurities in the mix produced a green-yellow tinted glass. One of the main uses for forest glass was church stained glass windows.
In sixteenth-century England, an embargo was placed on the use of wood-fueled furnaces for glassmaking, due to the deforestation it was creating. Glassmaking would move North, where good sources of coal would soon fire a new generation of furnaces.
Broad Sheet Glass
In this refined muff glass process, a longer cylinder was made by repeated gathering, blowing, and swinging the molten glass. The cylinder was slit, whilst still hot, before being flattened on an iron plate.
Wealden Glass Production: Tudor glass making was first centred around Chiddingfold, Surrey-Sussex, and later glassworks in Staffordshire. They supplied broad glass to the whole of Tudor England, the delicate cargo being delivered by pack-horsed to its destination.
The influx of Huguenot refugees brought a wave of glassmakers to Chiddingfold and the surrounding areas. This wave brought new technologies and techniques that greatly improved the industry, including the production of coloured glass.
In 1567, refugee Jean Carré arrived in London from Antwerp and obtained a crown-sanctioned patent for the production of window glass. A 21-year patent was awarded to Carré on the condition that prices remained low and that glassmaking and blowing would be taught to native Englishmen.
This glass was of poor quality and fairly opaque with many imperfections caused by bubble tracks, strain lines and tooling marks. Church leadlight windows and the 17th-century latticed lights of iron window frames were made using broad glass.
A ‘gather’ of molten glass was blown into a balloon using a blow-pipe. The blowpipe was ‘cracked off’ and a ‘punty rod attached. This ‘bull’ of glass was opened outwards and then spun on the solid “punty” rod. Using centrifugal force in this way formed a disc, known as a ‘table’, that got thinner toward the edges. This table was then cut into individual panes and a 12″ x 8″ pane would be considered large. Arched fanlight windows above front doors made efficient use of the tables rounded edge.
In the centre of the table was the bullion or ‘bulls eye’, the thickest part where tooling had been attached to the disk. This bulls-eye glass was the cheapest pane, due to the obvious defect, and so was usually reserved for servants quarters, the rear of buildings or small workman’s cottages.
Glassmakers from Normandy first introduced spun glass to England, as early as 1568. This ‘Normandy glass’ was kept a trade secret of the French glassmakers who had been producing it since the 1320-1330s.
Crown glass was first made in London in 1678 and by 1691 John Bowles had patented an invention to produce larger, better quality glass and introduced a crown emblem trademark to distinguish his high-quality goods. Soon all window glass produced in a similar manner became know as crown glass.
Whilst crown glass provided superior ‘fire finished’ brilliance and clarity over the broad glass, its popularity and adoption owed as much to the tax laws of the time as to the superiority of the product. Spinning during production had created a thinner, lighter pane than blown glass, at a time when glass was being taxed by weight. Consequently, by the l8th Century, most window glazing was crown glass because this thinner, lighter glass avoided higher tax rates. The building boom of the 1820s saw crown glass production rise from 86,00 t0 140,000 cwts per year.
Crown Glass Identification
Crown glass may be identified by a lustrous, irregular surface with concentric ripple lines and imperfections, created during rotation. The surface is slightly convex or concave with a bright finish.
Whilst crown glass is no longer made, much still remains in Georgian windows. The closest match available today is handblown European cylinder glass or specialist restoration glass.
Cylinder glass is a type of hand-blown sheet, created in a similar process to broad sheet. Larger cylinders were produced by swinging the cylinder in a “swing pit” trench. The glass was allowed to cool before the cylinder was cut and reheated in the flattening kiln. During flattening the cylinder is opened and pressed out “flat”, which could include up to three inches of variation across the whole sheet. This method created much larger panes of glass than crown production, with better surface quality and clarity than broad sheet.
In 1832 Chance Brothers glassworks of Smethwick, Birmingham made the first British cylinder blown sheet glass, using French and Belgian workers. During 1834 Robert Lucas Chance introduced ‘improved cylinder glass’ using a German process to produce finer quality and larger panes. Production capability went up from a 3 foot to a 4-foot length of glass, as used for the Great Conservatory at Chatsworth in 1837.
Once the glass tax was abolished, in 1845, cylinder glass replaced crown glass as the prefered option for glazing most windows during the second half of the 19th Century. Larger panes removed the necessity for many glazing bars and many late Victorian window sashes included only a single pane of glass.
Hand Blown Cylinder Glass Identification
Fine quality glass with a slight wavy reflection that is still commonly seen in Victorian buildings. Pit marks in one face are caused by imperfections transferred from the flattening surface.
Current production handblown cylinder glass from Europe is a good replacement for window conservation.
Polished Blown Plate Glass
Plate glass was produced by the lengthy and expensive procedure of grinding thick panes flat before polishing them clear, to achieve a flatter, less distorted glass.
British blown plate glass was first made in 1620 by hand grinding and polishing broad sheet glass. In 1839, a new process to grind the surfaces of plate glass was patented by James Chance.
Only a small amount of hand-blown glasses were polished into plate and mostly used to produce mirrored ‘looking glasses’. By 1845 cast plate had displaced blown plate production.
Polished Cast Plate Glass
Produced by casting glass onto a table and subsequently grinding and polishing the glass smooth and clear. Molten glass poured onto an iron table would cool quickly, resulting in a rippled surface. In order to achieve a flat surface, the glass had to be cast almost twice as thick as required and then ground down, using sharp sand, before fine polishing with metal oxides.
In 1688 the royal French glassmakers Saint-Gobain introduced a method for producing larger sizes by casting and polishing slab glass, it was primarily used for mirrors. Ravenshead produced the first English cast polished plate in 1773 using these French methods.
In 1848, the English innovator Henry Bessemer pioneered the automation of glass manufacturer. He devised a method to produce a continuous glass plate by using rollers. The final product obtained by this process was not flat and still required polishing. Bessemer also conducted the earliest experiments for floating glass on molten metals, that would later be perfected by Pilkington.
1854 Patent. ” Chance Glass Works, near Birmingham, in the county of Warwick, has given the like notice in respect of the invention of “improvements in machinery for roughing or preparing the surfaces of glass.”
With an end to the glass and window taxes, along with steam-powered manufacturing processes, prices dropped and soon 1/4″ thick polished plate glass was commonly used for Victorian shopfronts and other large windows. By 1872 Britain was producing 7.5 million feet of plate glass per year.
Polished plate glass was regarded as the most superior of all glazing until float glass was developed in 1959.
Polished Plate Glass Identification
Quality was generally good with only minor distortions or flaws. Polished plate is no longer produced and float glass provides the closest match for conservation purpose.
Mechanically Processed Glass
Before the Float process was developed, by Alistar Pilkington in 1959, flat glass was sold as either ‘window glass’ (drawn glass) or ‘plate glass’ (ground and polished).
Cylinder drawn sheet
Long cylinders of glass were drawn vertically from a circular tank then annealed before being split into smaller cylinders, cut and flattened.
The first mechanical process used for making glass in Britain used circa. 1910 – 1920.
Machine drawn cylinder glass has characteristics very similar to handmade cylinder glass, but may show visible draw lines, all pointing in one direction, from the process.
Flat drawn sheet glass
The Fourcault process, developed in Belgium in 1916, was first used to create flat drawn glass. Molten glass is drawn straight upwards, five storeys, from the heated vat, cooling and solidifying as it leaves. Thickness variations in the finished sheet are caused by gravity, small temperature changes just out of the vat and the mechanical rollers.
The quality of drawn sheet was later refined by other processes inc Lubber, Colburn and Pennvernon methods.
British production started around 1919 and for many decades 2 – 4mm thick flat drawn glass remained the most popular window glass. By 1945 Belgium was the leading worldwide producer of drawn glass.
It is a clear glass with slight thickness variations and distortions, often with a noticeable uniform wave that was created by the rollers. Small bubbles are known as ‘seeds’ or small grains of trapped sand, ‘stones’. Another optical defect is known as ‘music lines’, the result of contaminants that altered the density and therefore refractive index of the glass. Easily recognised as a wave resembling a line of written music.
This glass remains common in older 20th Century houses. Horticultural sheet glass or float glass are options for window conservation.
Ground and Polished Plate
The first UK production of continuous polished plate glass started in 1923, using a single grinding system. By taking the molten glass from a tank, instead of a pot, allowed a thinner rough glass to be produced. The rough glass used to produce a finished sheet 6.4 mm (1/4 inch) thick was reduced from 10.6mm to 8.6mm, a huge saving in the grinding process.
“This new twin grinding process replaced the semicontinual grinding and polishing processes used before and involved mounting tables holding glass onto cars that travelled on rails under a series of grinding heads. After passing under these grinding heads, which were fed progressively finer sand, the glass was washed and then ground smooth in the same manner. The surface was again washed, and the tables passed under the polishers. At that point the plates were half finished. They were removed, inverted and sent through the system again.” [Scholes]
By the middle of the late 30s, Pilkington had developed the ‘twin’ machine. Rollers squeezed molten glass into a ribbon which was ground on both sides simultaneously, before polishing. These developments gave Pilkington an international advantage in plate manufacture which they shared by licensing the continuous and the ‘twin’ grinders overseas.
After World War II plate glass was in short supply, the majority of production went for automotive glass, with some commercial window glazing.
A superior quality glass without distortion.
Tinted Polished Plate became popular in the mid-1950s, up to that point plate production had mostly been clear.
Tempered Polish Plate is made by reheating and sudden cooling, making the glass typically three to five times stronger than ordinary plate glass with the same thickness and appearance. After being tempered it can no longer be cut.
Laminated Plate is two sheets of plate sandwiched around and adhered to a plastic inner layer.
Rolled Sheet Glass
Due to the scarcity of common sheet window glass during the war Chance Brothers experimented to produce an effective substitute. Using ‘specially colourless materials a rolled glass so transparent that it served many of the most important uses of ordinary sheet glass, and for several purposes will probably displace it” Large quantities were used for public and commercial buildings.
Although it was advertised as ” Stronger : Whiter : Cheaper” and “Comparable with common 21oz sheet glass” it never found a dominant role in the market.
A continuous wide ribbon of molten glass is floated over molten tin. The glass floats on top of the tin and solidifies as the temperature is reduced.
In 1959 Pilkington introduced float glass, which eliminated the need for grinding and polishing to achieve a flat glass. The modern production of float glass is very efficient and can ‘operate continuously for up to 12 years—making over 50,000 miles of high-quality flat glass almost automatically.’
Alastair Pilkington, who was an employee and not related to the Pilkington Brothers, is credited with inventing float glass. He wanted to find a way to make glass as perfect as plate glass at the lower cost of sheet glass. As the legend goes, he found his inspiration while washing dishes in 1952. He noticed one of his dinner plates floating in the sink and realized that if he could take the ribbon of sheet glass out of the furnace and float it on a liquid surface, it would come out perfectly smooth without needing pressure plates.
Libbey Owens Ford Glass Company, Ohio USA, had also been actively developing a ‘Glass on Metal’ process. Their experiments with casting sheet glass over a tank of molten aluminium were not as successful as Pilkingtons, using tin.
A flat, optically near-perfect sheet with even thickness. The perfectly flat finish presents a lifeless character in comparison to the traditional hand-blown glasses of period homes.
Float glass is the standard glass we still use today. Since the 1960s 3mm float glass was the standard glass used to glaze homes, although larger panes and newer buildings may be 4 mm or thicker.
Glass is a highly versatile medium. In its molten state, it can be spun, blown, rolled, cast in any shape or tinted any colour. Once cooled, it can be polished, bevelled, chipped, etched, engraved, or painted.
Since early times coloured glass had been used in church windows and by the 1830s coloured or stained glasses were frequently used to ornament staircase windows. The Victorian Gothic Revival started an ongoing industry that has focused on developing coloured and patterned decorative glass. The second half of the nineteenth century was the ‘golden era’ of decorative glass discovery with wide range of new textures, colours and patterns introduced.
Coloured glass predated clear ‘white glass’ because metal impurities in the sand, the soda, and even the clay that was used to form the furnace and pots would result in a tinted glass. When glass was made using kelp ash as the soda, rather than wood ash, it was found to darken from yellow to a ruby colour through repeated firing.
The alchemy for producing vivid medieval coloured glasses was virtually a lost art by the eighteenth century. The Victorian chemists were confounded in their search to recreate those vivid colours because the state of the metallic solution gives rise to quite different colours. For example, ‘ferric iron’ produces a yellowish-brown whereas ‘ferrous iron’ produces a sage-green. Eventually, the recipes for creating vivid blues, greens, yellows, browns, purples and reds were rediscovered.
Lead or Sulphur compounds give rise to yellows, Chromic and Nikel salts produce green glass, Cobalt provides the finest blues whilst copper displays a peacock blue. White opaque glass is made with antimony.
Yellow glass was particularly difficult to perfect in the desired shade, and free from blisters. Special processes of melting at lower temperatures along with precise measurement of the ingredients was necessary.
“Uranium is one of the rarer and more costly elements, but is nevertheless used in glass-making for special purposes on account of the very beautiful fluorescent yellow colour which it imparts when added in small proportions. This yellow is quite characteristic and unmistakable, so that none of the other varieties of yellow glass can ever be used as a substitute for uranium glass.”
The search for a red glass that was not so dark that it stopped light passing through it was a challenge. ‘Flashed ruby glass’ was made by ‘flashing’ a thin layer of the dark red glass (created using copper) to a thicker body of clear glass, enabling the light to shine through. Later it was rediscovered, by Antonio Neri in 1612, that adding very low concentrations (around 0.001%) of Gold produced a long-lasting ‘Gold Ruby‘.
The colouring effect of gold is undoubtedly more regular and uniform than that of copper, and it is accordingly possible to obtain much lighter shades of red with the aid of the noble metal. “Gold ruby” can, therefore, be obtained of a tint light enough to be used in sheets of ordinary thickness, and the process of “flashing” is not essential.
“When the pieces of ruby glass have been cut to the shapes for the purpose for which they are to be used comes the operation of colouring; this is done by placing the slabs of glass in the kiln and slowly raising the temprature almost to the softening point. If the glass is watched during this rise in temperature it will be seen to pass from the faintest and most beautiful of rose tints, through the rare pigeon-blood ruby to the deep purple-ruby that once seen is never forgotten. If the firing is pushed beyond this stage the metal becomes blue and if still further forced the particles of gold so coagulate that the metal may become rusty and all its beauty is lost”
Red and true Yellow glasses remain the most expensive colours to this day.
Opalescent glass is where a streaky colour is fused into a milky opaque glass during manufacture. Its production was perfected in the United States and commonly used in leaded light windows.
Ambetti Glass is a type of glass, containing small, opaque specks.
Stained glass is different from coloured glass because the surface applied tint does not penetrate right through the body of glass.
Introduced to Europe, from the Middle-East, at the end of the 13th Century. Metal salts were mixed with clay, applied to the surface and fired. When rinsed clean the surface would have a permanent stain, the intensity of tint depending on kiln temperature and duration of firing. Silver salts produced pale lemon to deep orange, even brown, Copper salts produce reds.
1760 William Beilby became the first man in England, possibly the world, to fuse painted on enamels into the glass surface. Commonly used as quarries in leaded lights and for commercial signage in shopfronts and pubs.
Patterned / Figured / Cathedral Glass
Patterned glass was made by embossing hot glass with rollers, either on a table or later by machine.
In the 1840s James Hartley of Sunderland was granted a patent for embossing a pattern into the surface of a cast sheet. The design was engraved into a cast iron table, the hot glass poured and then rolled flat from above with giant iron rollers. The designs were simple ribs or diamonds. Hartley’s Patent Rolled Plate’ was produced for over fifty years but most of this production was as glass roofing tiles. Hartley licensed his patent and soon other glass works were producing rough rolled sheets and tinted cathedral glasses.
In 1888 Chance Bros introduced machine rolled patterned glass by using an additional pair engraved ‘pattern rollers’. These rollers required expert engravers to produce a roller that could imprint an uninterrupted, seamless pattern.
The hot glass was first passed through flattening rollers, to achieve a consistent thickness, before the pattern roller embossed its pattern into the upper surface. Opposite the pattern roller was a smooth roller to smooth the lower face. By the end of the century, continuous-casting techniques were in place whereby the pattern was embossed by the lower roller, speeding up mass production.
This patterned and often tinted glass was sold as ‘Cathedral Glass’ although it has nothing to do with medieval cathedrals, where the glass used was hand-blown. Rolled glass is not as rich or translucent as hand-blown glass, but it is much cheaper and is made in a variety of colours and textures.
In the mid-19th century, it became fashionable to use decorative glass extensively in front doors, side lights and transom / fanlights. Many new textured and frosted designs appeared and sometimes small panes of glass were painted with birds, flowers or geometric patterns.
“Chance’s Flemish Glass A new product of the famous glass works of Chance Bros. & Co., Limited, near Birmingham, England. “Flemish” is a new and most attractive variety of Ornamental Window Glass, unsurpassed in character and brilliancy.” 1911
Old Glass Patterns & Colours
Displayed here are just some of the most popular patterns.
See our supplement page with extensive galleries of figured and coloured window glass.
Glass etching or “French embossing,” is a popular technique developed during the mid-1800s that is still widely used. Parrafin wax or (later Brunswick Black) would act as a ‘resist’ when painted onto the surface. A decorative pattern is then stencilled or scratched into the wax layer, exposing the glass surface. Hydrofluoric acid vapour soon etches into the smooth glass surface, creating a frosted and clear decorative design. Acids, alkali or physical abrasives can all be employed to achieve a similar effect.
“Embossed Glass is a polished plate glass 1/4 of an inch thick with designs embossed in it. The embossing is done by first stensiling the pattern in Brunswick Black. The surface is then subjected to the action of fluoric acid, which attacks and makes a ground glass surface on the unprotected parts. Embossing is done to suit the particular size as the occasion demans”
In the 1920s a mould-etch process was developed, where the design was etched directly from the mould. Each cast piece emerged from the mould with the image already etched into the surface of the glass.
Acid etching can revert to become an almost clear pane when wet, which should be considered if selecting etched glazing for bathrooms or other wet environments.
Sand Blasted Glass
Sandblasting will also etch into the smooth polished surface. Unique patterns can be sandblasted by using a shaped ‘mask’ or ‘resist’. The finely pockmarked surface becomes opaque but is also prone to marking, notably from oily fingertips. Modern frosted glasses do not suffer in the same manner.
Glue Chipped Glass
This pattern is created by applying hot animal glue to a sandblasted surface of sheet glass. As the glue dries, and contracts, it pulls flakes of glass off the surface in a random fashion. It has been used since the late 1800s, clear or tinted. Using a stencil, many shop signs or decorative patterns were created this way.
This decorative glass is made by silver and gilt wire designs filled in with different coloured granular glass, fastened with translucent cement and hermetically sealed between double glasses to prevent dust or moisture penetrating. Unlike lead light, the design is transmitted both sides. The maximum sizes was 9in. x 4 in.
Lead Lights & Stained Glass
Leadlights are glazed panels constructed from small pieces of glass called ‘quarries’ and joined together with ‘H’ shaped lead strips called ‘Cames’. All manner of decorative patterns were created by the leadlighter, using the whole spectrum of coloured and patterned glasses, as well as bevelled or moulded quarries shaped into patterns such as fleur de lys or bulls-eye roundels.
Quarries used during the 19th century were often made by James Powell and Sons of Whitefriars, London. As the Victorians were building hundreds of Gothic Revival churches, Powell & Son emerged as a leading producer of stained glass. Another major product of the factory was decorative ‘quarries’ which were cheaply moulded and printed, rather than hand-cut or painted.
Australian Stained Glass & Leaded Lights
From as early as the 1840s, stained glass was being imported into Australia from Britain. John Hardman & Co of Birmingham and Clayton & Bell of London, amongst others, supplied thousands of stained glass panels to Australia in the nineteenth and early twentieth centuries. By the 1860s stained glass firms had started production in Melbourne and Sydney, launching an industry that thrived from 1860 to 1920.
Leaded Light Styles
From the 1860s to the 1930s leadlights were a regular architectural feature in many homes, public houses and hotels. The style of pattern often provides a clue as to the age of a building.
- The 1840s Gothic Revival brought about new popularity for diamond-pane windows in homes of the wealthy.
- The Arts and Crafts (1880 and 1920) designs often included flowers such as lilies and tulips.
- The late Victorian leadlights often contain small rondels with grey painted depictions of birds or flowers.
- Later the Victorians used leadlight extensively in and around doorways but prefered large clear glass for their sash windows.
- Edwardian era leadlights decorated not only doorways but the top of windows as well.
- The Art Nouveau and Art-Deco period window and door panels incorporated many long curved sections of leaded glass. During this period zinc was often used in place of lead to make zinc-lights, commonly featuring clear bevelled and clear textured quarries.
Quarries & Special Glass
Priors Early English Slabs (Also Chances similar glass called ‘Norman’) were made by blowing coloured glass into a box and when solidified cut into rectangles. The squares were thicker in the centre, tapering out towards the edges. The streaks, imperfections and richness of the glass made it ideal to use in Arts & Crafts windows. Priors Glass was first blown in 1889 by the firm of Britten & Gilson of Southwark, London.
A monochrome painting method, usually grey, that produces a more 3-dimensional like effect.
Stained glass windows usually depict a painted picture or scene, each piece handpainted and fired before being assembled. Leadlight windows differ from stained glass windows principally in being a less complex design that rarely included painted components.
Stained glass windows were first developed in France and the first stained glass to be produced in Britain was made in Sunderland by French craftsmen imported from Gaul, in AD674. Benedict Biscop, Abbot of the new monastery at Wearmouth, invited them to make the windows for St Peter’s Church. Stained glass helped to educate a largely illiterate population to the stories of the bible.
Other Glass Processes
Bowed or bent windowpanes are made by slumping. A glass sheet is placed in a mould and heated from above. Between 500°C and 600°C the viscosity of glass falls as it transforms from a brittle solid to a plastic substance. When this plasticity is reached the glass sags or slumps into shape, without marking its surface.
Tempered / Toughened Glass
Tempering is a process of heating the glass before suddenly cooling the surface. Too much heat and the glass becomes distorted, too little and it doesn’t temper. Uneven cooling may cause the sheet to crack. Consequently, only one pane in ten could be successfully tempered until French glassmakers St. Gobain automated the process in the 1930s. Pilkington obtained an exclusive licence for production of toughened glass in Britain.
Once tempered, glass can no longer be cut without shattering, so the pane must be cut to size before the heat tempering process. Tempering produces a safety glass that is 3 to 5 times stronger and will shatter into many pieces if broken, reducing the chance of injury.
Tempered safety glass can usually be recognised by a small etch mark in one corner.
In 1909, Edouard Benedictus patented TriPlex, a laminate created using two glass sheets bonded with an inner layer of clear plastic.
Benedictus was a French theatre set and costume designer with an interest in chemistry. He had earlier broken a clear glass chemistry flask, that somehow managed to stay together. He discovered that an invisible plastic film had formed on the inside, residue from the last contents, that had held the broken glass together. In 1936 the inter-layer was changed from celuloid, that had turned yellow over time, to a more stable plastic film.
Pilkington developed a process for making thin plate glass and in 1929 Pilkington and Triplex Safety Glass Co formed a joint company to produce laminated glass in St Helens.
In 1898 Pilkington introduced Hexagonal Rolled wired cast glass.
Georgian wire polished plate glass has a wire mesh embedded during production. In case of breakage, the glass will stay together making it suitable as security and fire-resistant glass. Wired glass is actually weaker than unwired glass, due to the incursions of the wire into the structure of the glass, but will remain intact for longer in case of fire. Later development resulted in ‘Safety wired glass’ that looks like traditional wired glass but incorporates a safety film.
” WHEREVER light is required and Loss and Injury can occur through breakage of Glass, there is the need for Pilkington s Patent Fireproof Wired Glass. Fire cannot pass through it. It with-stands the fiercest heat, as long as Iron of equal thickness. Stones and other Falling Material are arrested by it. Burglars and Housebreakers are toiled by it. Insurance Premiums are reduced by it. Practical experience in all parts of the world under widely varying conditions has proved it.” 1911 Pilkington Bros.
Chemical vapour deposition (CVD) deposits a thin coating on the glass by exposing the hot surface to chemical gases. The resulting coating is hard, uniform and extremely thin. CVD coating is the most significant advance in the float process since it was invented.
This coating method can lay down a variety of coatings, less than a micron thick and multiple coatings can be deposited in just a few seconds. As new coatings are developed new characteristics become possible including self-cleaning, reflective and electrically conductive surfaces.
Low-E, Energy Efficient Glass
Traditional window glass is not energy efficient, providing only slightly more thermal insulation than nothing at all. In 1989 a CVD applied ‘invisible’ coating of tin oxide was developed that makes float glass more energy-efficient by reflecting visible and infrared wavelengths.
Insulating Glass / Double Glazing
First developed into a commercial product in the 1930s. Early double-glazed units consisted of two sheets of plate glass separated by a continuous lead strip soldered to the glass sheets at their perimeter.
Heritage Glass Conservation
The subtle imperfections of heritage glazing add a character to the appearance of period windows, that modern float glass can not match. Before any decision is made to replace period glass serious consideration should be given to the inevitable change in appearance and loss of authenticity.
A single pane of float glass clearly stands out when sat side-by-side with crown or cylinder glasses. Selecting the closest match for glazing repair work may be more expensive, but will blend in far better.
Salvaging old glass can be a delicate and time-consuming process, but it does ensure the best heritage conservation standards. At Sash Window Specialist we try to salvage as much old glass as possible but our stock is variable. The most successful way for extracting old glass is to dismantle the timber sash frame.
Horticultural Sheet, also known as greenhouse glass, is produced by a later variation of the flat drawn sheet process.
As an alternative to smooth float glass it does have some visible surface distortions and blemishes, but the uniform wave created by rollers is no match for the surface of handmade glass. Good quality batches of horticultural glass can provide a cheap, easier to source glass for some restoration purposes. However, optical qualities are not a priority during its production and batches vary considerably with regards to clarity and surface marking, reducing its suitability as a good quality window restoration glass.
European Cylinder Glass
Various cylinder glasses are still manufactured in parts of mainland Europe. Whilst some are sheet glass is produced for restoration purposes most are ‘art glasses’. Art glass is used in leadlight and other decorative work that may have an exaggerated surface distortion or high bubble count. Available from specialist glass suppliers.
Specialist restoration glasses with a flawed surface, like Barley Bent and GoetheGlas™ have recently been introduced. A modern wavy glass that can be laminated or even used in a double glazed unit.
Decorative glasses present the biggest challenge for conservation because most original patterns are no longer made. A matching period glass may occasionally be reclaimed but for larger panes substitution with a similar modern pattern is usually the only option.
Leading glass manufacturers provide an economical range of popular modern patterns in large sheets. For smaller panes specialist stained glass suppliers offer a wider range of options. Recreating patterned and coloured glass can be achieved by laminating a clear patterned glass to thin coloured glass. Alternatively, decorative window films can offer a cheaper alternative.
Lead lights can be repaired and restored by specialist glaziers. Lead oxides in old cames are toxic and need to be handled accordingly. Often the whole panel must be removed and the lead came’s replaced. It is expected they will need to be re-leaded about every 100 years.
Clear float glass is available in a range of thickness.
- Low-E coatings, that improve energy efficiency, can be baked into the surface during production.
- It can be tempered with heat, to produce a stronger safety glass.
- Surface etched patterns
Obscured / Patterned Glass
Patterned glass is available in a range of thicknesses dependent on the design. Specialist glass suppliers also offer small batches with alternate patterns.
Manufactured by bonding multiple panes of float glass together, with a thin inter-lay film sandwiched between the glass layers. Laminated glass has many benefits including greatly reduced ultraviolet (UV) light ingress, Grade A safety glass, improved security as well as improved noise reduction.
Laminated glass that incorporates a ‘smart’ interlayer. The interlayer is designed to dampen noise and may reduce noise by up to 40% in comparison to similar thickness float glass.
Two panes of float glass separated by a void to improve thermal insulation. The thickness of the void is dictated by the spacer bar. A black resin ‘hot melt’ seal is applied around the perimeter to prevent moisture entering the void, where it could condense and mist up, on the coolest of the inner surfaces.
Low-E Sealed Units
Low Emmisitivity or ‘Low-E’ are energy efficient double glazed units that include a pane of Low-E glass and a void filled with Argon, or another inert gas, instead of dry air.
Vacuum Insulating Glass
The first patent for Vacuum Insulating Glass (VIG) was made in the 1930s and during the following 75 years, many attempts were made to develop this concept. Nippon Sheet Glass Group launched Spacia in 1996 for the Japanese market. The process has continually been refined and recently Pilkington (owned by SSGG) launched Spacia into the British market.
A vacuum between the two sheets is even more effective at minimising heat transfer than a gas-filled void. To prevent the two panes from flexing inward minute pillars act as spacers. Pilkington Spacia has just 0,2 mm vacuum gap, giving the unit an overall thickness of just over 6 mm. Radiant heat flow is limited through one of the glass panes by a low-e coating. It offers high levels of thermal insulation, a very reliable hermetic edge seal as well as reduced thickness and weight.
VIG products made by other manufacturers are in the market or under development. VIGs are also being used in hybrid glazings and laminated assemblies. As competition increases and prices fall VIG will be an increasingly attractive choice in the market for high performance thermally insulating glazing.
The evolution of architectural glass has had a huge impact on our buildings and the way we live in them. The simple muff glass process, used by the Romans, developed into a global industry making giant cylinders of mechanically drawn glass. The Georgians started a movement towards larger glazed areas by joining small panes of hand-blown glass using timber glazing bars. A trend that has culminated with today’s buildings being clad entirely with walls of laminate sheet glass.
The ongoing development of flat glass was perfected with the float process. A perfectly flat, optically pure glass that is relatively cheap. However, for the conservation of historic windows, this glass is out of place. The wavy imperfections of hand-blown glass create reflections in a dappled, softer and more interesting way than float glass. Owners of period property wishing to modernise face the choice of preserving this unique, but thin and energy inefficient glass, or replacing it with modern insulation glasses.
CVD coatings are opening up new possibilities for glass that will change how we use it in our buildings and the vacuum insulating glass technology is still in its infancy. In the future maybe will we be fitting vacuum-sealed triple glazed units, with a wavy replica finish, that can also become frosted on demand, whilst a photovoltaic film generates us clean power? Scientist and glassmakers are already well on the way to making this a reality…
Flat and optically perfect glass is now a thing taken for granted, but we have many generations of skilled and inventive glassmakers to thank for bringing the sunlight into our homes and brightening our lives.
British Glass, 1800-1914 – Charles R. Hajdamach
Windows: History, Repair and Conservation – Michael Tutton
A Merseyside Town in the Industrial Revolution: St. Helens, 1750-1900 Chapter XVI: ‘The Glass Industry 1830 – 1845’
Tariff of the Prices of Polished Plates of Glass
Twentieth-Century Building Materials: History and Conservation
Products that do not directly relate to the windows we regularly encounter and so did not make the main article. These window glasses are most likely encountered in former industrial or commercial buildings.
Luxfer and Pilkington are the best-known names in prism glass. The Luxfer Prism Company started life in October 1896 as the Radiating Light Company, founded by James Gray Pennycuick to commercialize his patent No. 312,290 for “an improvement in window-glass” (filed 1882, granted 1885). His improvement was the addition of horizontal prisms to the back side of square glass tiles, which redirected sunlight from windows where it was plentiful, back deep into rooms where light was scarce, reducing the need for artificial lighting and light wells.
Through the Healing Glass
Shaping the Modern Body through Glass Architecture, 1925-35
In the mid-1920s a physiologist, a glass chemist, and a zoo embarked on a project which promised to turn buildings into medical instruments. The advanced chemistry of “Vita” Glass mobilised theories of light and medicine, health practices and glassmaking technology to compress an entire epoch’s hopes for a healthy life into a glass sheet – yet it did so invisibly.
To communicate its advantage, Pilkington Bros. spared no expense as they launched the most costly and sophisticated marketing campaign in their history. Engineering need for “Vita” Glass employed leading-edge market research, evocative photography and vanguard techniques of advertising psychology, accompanied by the claim: “Let in the Health Rays of Daylight Permanently through “Vita” Glass Windows.”
Despite the best efforts of two glass companies, the leading marketing firm of the day, and the opinions of leading medical minds, “Vita” Glass failed. However, it epitomised an age of lightness and airiness, sleeping porches, flat roofs and ribbon windows. Moreover, through its remarkable print advertising, it strove to shape the ideal relationship between our buildings and our bodies.
1933 “Calorex” is manufactured by Messrs. Chance Bros, and Co. Ltd. of England, and is being distributed in New South Wales by Messrs. F. W. Gissing Ltd
“SUNLIGHT WITHOUT DISCOMFORT A Vital Glazing Problem Solved Every building needs windows for the very obvious purpose of admitting daylight. Until recently, however, it was impossible to secure this solar illumination without the accompaniment paniment of sun glare and heat, unless the window glass was either painted regularly or shielded with blinds. These expedients, whilst in some measure minimising the undesirable elements in sunlight, resulted in a disproportionate tionate sacrifice of natural light. Many an architect must have asked himself: self: “Is there any way of economically overcoming coming the discomforting and deleterious effects of sunlight without seriously affecting the natural lighting of the building?” That was a vital problem and remained unsolved until scientific research and exhaustive tests culminated in the production of “Calorex” glass. In this remarkable product are combined the seemingly irreconcilable qualities of admitting light and excluding heat. Tests have definitely ly proved that “Calorex” glass cuts off 80 per cent, of heat while transmitting nearly as much light as ordinary glass, thereby saving all the expense of sunblinds or shutters, painting, or artificial’ light during daytime. “Calorex” glass is manufactured in various types or patterns to suit all forms of indoor activity, industrial and otherwise.” Chance Bros
Coldlite anti-actinic glass
Australian heat-absorbing glass to allow maximum amount of light combined with cool working conditions in summer. c 1940
COLDLITE ANTI-ACTINIC HEAT-ABSORBING GLASS. For use in reducing the intensity of solar radiation, and the consequent access of heat to buildings glazed with this glass. “Coldlite” is of a delicate bluish-green tint and most soothing to the eye. Particularly is this the case in very strong sunlight, as the glass absorbs practically all glare resultant from extreme treme light intensity. “Coldlite” transmits almost 70% of the visible light and only 15% of the total solar infra-red (heat rays) and essentially no ultra-violet. The glass is specially recommended for use in northern and western exposures of buildings whether residences, office buildings, factories, warehouses or stores, and in fact in any type of building where protection from infra-red (heat) radiation or high natural temperature is essential without sacrificing visible light, and when so used will greatly add to the comfort of those persons living or working in such buildings, due to the reduction of transmitted heat. The reduction of transmitted heat is very desirable and necessary where delicate fabrics (particularly “doped” fabrics as used for aeroplane plane construction), rubber goods, etc., are stored, as these goods are unduly affected when stored in hot places. Similar remarks apply with coloured goods where the colours are affected by the infra-red rays, and due tc the absorption of the infra-red by the glass the rays do not penetrate to the building and thus cause destruction truction or deterioration. “Coldlite” will also assist in diminishing, to some extent, the danger of spontaneous combustion bustion in warehouses and garages. It should be noted that this glass is in no sense of the word an insulating glass, except insofar as it absorbs radiant energy. In point of direct conductance of heat through the glass, it is little more effective as an insulator than is any other type of glass. In other words, except as it excludes direct solar radiation, it will have little effect in controlling temperature conditions within a building. This special bluish-green glass is made from a formula designed to withstand the severe atmospheric changes to which it must be exposed, posed, it is uniform in colour and efficiency, and without a doubt will become a factor in the glazing of buildings with the development of air-conditioning. It has been proven that employees working in moderate temperatures during the summer months work with increased efficiency, as against those who work in buildings where the heat is uncomfortably great and as the passage of infra-red light is only prevented to a very small degree by glazing with ordinary glass, conditions in hot climates or in the summer in factories or buildings are thus too hot for efficient working. When such buildings, however, ever, are glazed with “Coldlite” Anti-Actinic Glass, the transmission of the infra-red light (which in the ordinary course of events is absorbed by objects in the room and converted into heat) is practically eliminated, and thus conditions become more comfortable.
In the mid-nineteenth century, three key innovations helped to improve the sheet glass industry.
- 1862-3 The Siemens regenerative furnace was more economical on fuel. The furnace was awarded a Grand Prize at the Paris Exhibition of 1867.
- 1870 The Beivez lehr (cooling oven) reduced annealing time from eight hours to thirty minutes
- 1873 The Siemens tank furnace made glass melting a continuous process and replaced the traditional pot furnace.
British Flat Glass Companies
Many glasshouses existed across the country producing tables of crown glass before a recession hit in the early 1840s, causing many to close.
Sheet glass producers had initially gained a financial advantage by exporting most of their production, selling little to the highly taxed domestic market. Exported sheets had to be rectangular panes, with tax concessions to ‘write-off’ waste glass created by cutting crown glass tables into squares and discarding the bulls-eye. Sheet glass created no such waste, but still the producers benefitted from the taxation system.
With an end to both glass and window taxes, domestic demand moved from small panes of thin crown glass to the large sheet glass. The sheet glass manufacturers were Chance Brothers of Birmingham, James Hartley and Co of Sunderland, Cooksons of Newcastle and Pilkington Brothers of St Helens. By the time of the building boom in 1845 ‘a famine of sheet and sheet plate glass‘ existed in London as production failed to keep up with demand.
Glassmaking was an important North East industry since the 1600s when Huguenot glassmaking families settled there, after fleeing the first protestant persecutions in France. Between 1615 and 1642 the glass industry in England was dominated by Sir Robert Mansell, who bought the exclusive right to glassmaking in Tyneside.
By the 1820s, there were no fewer than forty glassworks within half a mile of Newcastle city centre. During the annual procession, glass-makers took part wearing glass top-hats and carrying glass walking-sticks, swords and pistols. By 1827 about two-fifths of all English glass was made in the Tyneside area. In 1845 South Shields was making more plate glass than anywhere else in England. In 1860 more than 1,000 glassmakers were employed in more than 20 companies, with glass being shipped all over Europe.
Hartleys of Sunderland
The Wear Glass Works was established at the junction between Trimdon Street and Hylton Road, Deptford, Sunderland c 1836. By 1865 one third of the sheet glass in England was supplied by Hartley Wood and Co Ltd from the Sunderland works.
1847 James Hartley invented `Rolled plate`. Hartley’s Patent Plate is also known as Hartley’s Rolled Plate, Hartley’s ridged glass or Hartley’s Patent Rough Plate and was produced until 1910-20s. In the mid-19th century uses for rolled plate glass included roofing railway stations and greenhouses.
” Alfred Wood, worked with Chance as a colour mixer until he departed with his recipes in 1893 to become a partner in Hartley Wood & Co. of Sunderland by 1895. On his arrival they made an Antique muff glass for the first time. Importantly, the quest of Pugin and Winston to find a glass that possessed similar qualities to medieval glass had focussed on discovering a good ‘StreakyRuby’. In 1849Pugin had used John Hardman to mediate with James Hartley, who sent him a variety of samples including a ruby sheet with a stain applied that needed to be fired in the kiln to ‘bring the colour out’. Winston was aware of Harley’s endeavours because Thomas Ward had also been encouraging Hartley to produce a streaky ruby for restoring medieval glazing and had shown the resulting samples to Winston.
In 1850: Charles Winston called attention to a piece of modern ruby glass, made by blowing, in express imitation of some ancient glass of the thirteenth century and early part of the fourteenth century, in March last year by MrHartley of Newcastle [sic], at the instigation of Mr Ward, the glass painter. This was Mr Winston believed, the first instance of such an imitation; and although the glass produced was not identical with the original model, yet it certainly came nearer to it than any other substitute. Thus, the ruby glass sold by Powell’s could be the same as that found in windows by Clayton & Bell or Morris & Company. However, although it may have been bought from Powell’s, this glass could have well been made by James Hartley.
Messrs Stock & Sharpe, lead and glass merchants, would have acted as agents to James Hartley, amongst others, who was regarded as the expert maker of crown glass and had moved from Chance of Birmingham in 1836 to start his own manufacturing works in Sunderland.
The Order Books of James Powell & Sons reveal that ‘Antique’ glass first appeared in 1858 in a reference to a ‘Flashed blue circle on Hartley’s Antique Ruby’, sold by the firm to Hale church near Salisbury. Over the next few years the Order Books record more references to Hartley’s ruby or ruby sheet.
“…encouraged him to source new glass, in particular, a streaky ruby that emulated medieval glass from the glass manufacturer James Hartley of Sunderland.”
Winston was aware of Hartley’s endeavours because Thomas Ward had also been encouraging Hartley to produce a streaky ruby for restoring medieval glazing and had shown the resulting samples to Winston
In 1849 Pugin had used John Hardman to mediate with James Hartley, who sent him a variety of samples including a ruby sheet with a stain applied that needed to be fired in the kiln to ‘bring the colour out”
In 1850 Charles Winston called attention to a piece of modern ruby glass, made by blowing, in express imitation of some ancient glass of the thirteenth century and early part of the fourteenth century, in March last year by MrHartley of Newcastle, at the instigation of Mr Ward, the glass painter. This was Mr Winston believed, the first instance of such an imitation; and although the glass produced was not identical with the original model, yet it certainly came nearer to it than any other substitute.
“Alfred Wood, also worked with Chance as a colour mixer until he departed with his recipes in 1893 to become a partner in Hartley Wood & Co. of Sunderland by 1895. On his arrival they made an Antique muff glass for the first time.”
the 1861Census lists a number of French glass blowers working in Hartley’sSunderland works who had moved with him from Chance, including Louis Andre)
In 1892, with the Wear Glass Works failing, James Hartley junior, established a second business making antique coloured glass at the Portobello Glass Works in Portobello Lane, Monkwearmouth. Alfred Wood became his works manager. James Hartley junior traded here as The Portobello Glass Co Ltd until March 1895 when he took Alfred Wood into partnership and the firm became Hartley Wood and Co. On 9 May 1908 the partnership was dissolved and Alfred Wood continued the business in partnership with his son, Alfred John Wood. In 1912 Alfred John Wood and his brother Gilbert Henry Wood bought out their father’s share of the partnership and established a new partnership. Alfred Wood died in 1916. In 1914 trade directories describe the firm as manufacturers of antique, ambitty and Venetian glass. Wikipedia
Although the Wear Glass Works had been very successful for over half a century, in the 1880s business began to decline because new plate glass manufacturing methods developed by rival firms were not adopted at Hartley’s. The company was taken over by Pilkington in 1982 and ceased operation in July 1989.
Hartley wear glassworks – Facebook
James Hartley & Co. Tarriffs : crown, sheet, and patent rolled, British polished plate, and coloured glass manufacturers, Wear Glass Works, Sunderland
Cooksons of Newcastle
Ouseburn Glassworks, Newcastle was the first glasshouse at South Shields around 1707. In 1756 they mortgaged the glasshouse to John Cookson.
Isaac Cookson had set up a glasshouse in South Shields for his son, John, in 1737. John Cookson entered into a partnership with a Thomas Jefferies to make crown glass there. On John’s death in 1785, the works passed to his son Isaac and the Cooksons remained the leading glassmakers in the district until the middle of the nineteenth century when the works passed to R. and W. Swinburne and Company, who manufactured glass here until 1876. In the early 19th century the largest glass manufactory in the kingdom. The works used the Ballast Wagonway to take waste to The Bents and to bring in coarse sand to use in grinding.
The Glassworks were acquired in 1892 by the Harton Coal Company and demolished.
“Now we know Cookson’s are more intent upon sales, without caring so much about quality” Fred Fincham, Ravenhead Manager 1835
A French Huguenot family probably began the first glassmaking in Sutton. Sand, coal and fireclay could be sourced locally with only the alkali having to be imported.
William Stock & Co Plank Lane Glassworks, Leigh Lancashire
Circa 1852: William Stock started the Plank Lane Glass Works, which was afterwards carried on by his son, Livesley Stock. At one time there were up to 150 hands employed to make Crown glass, and later blown sheet glass. Closed and demolished in 1893.
1884 “..four English firms which made window glass, namely, Pilkingtons of St Helens; William Stock & Co Plank Lane, eight miles from St Helens; Chance Brothers at Spon Lane, Smethwick; and Hartleys of Sunderland.” The Economic History Review
Pilkington Brothers of St Helens
Formerly The St. Helens Crown Glass Company founded in 1826. Renamed “Greenall & Pilkington” in 1829 as a partnership between members of the Pilkington and Greenall families, based in St Helens, Lancashire. In 1849, it was officially renamed Pilkington Brothers and soon flourished producing cylinder sheet glass. During the 1870s the Pilkington brothers set up a new factory to produce plate glass on the outskirts of St. Helens. By 1903 it had become the sole British producer, as other British producers had failed to compete with European imports.
Canada in 1906 was Pilkingtons biggest market for glass exports. “The size and profitability of these sales depend to a large extent on Canada not possessing its own flat glass industry”.
In 1931 Pilkington’s introduced from the United Staes the flat drawn process.
Pilkingtons development of the ‘twin’ machine’ for plate glass production gave them an international advantage that extended to become almost a monopoly with their later invention and licensing of float glass.
Pilkingtons was taken over by Nippon Sheet Glass, of Japan, in 2006.
“PILKINGTON was founded in 1826 in St Helens, England. The company remained in family ownership until 1970 when shares were issued on the London Stock Exchange.
During the last 25 years the business has grown in Europe, the United States, South America and Asia/Pacific. Eighty five per cent of the Group’s sales are now outside the United Kingdom.
The Group and its associates are the world’s largest manufacturers of float glass. The Pilkington float glass process revolutionised the manufacture of high quality flat glass. It is recognised as one of the major inventions of the twentieth century. Pilkington operates or has interests in 30 float plants in twelve countries. The process is licensed to 42 manufacturers in 30 countries. There are over 170 float plants worldwide with a combined output of 3000 miles of glass a day. Annually they produce a ribbon of glass over one million miles long.”
Casting Glass: Crucible Pots
The crucible pots used to heat the glass for polished plate constituted one of the greatest expenses. These crucibles were formed using a special pure fire-clay, that then required seasoning for up to a year. Each crucible held a ton of ‘metal’ and in the fierce temperatures of the furnace, each pot only had a working life of around 3 weeks.
The raw ingredients were mixed to become grey powder and then heated for seventeen hours in gas-heated furnaces. During which the contents loses bulk, requiring three more top-ups before being ‘charged’. At first, the metal is full of bubbles, but later becomes a clear liquid. The temperature is reduced for four hours and the glass skimmed for impurities before being ready for casting.
Although ‘forest’ glass was being made in wood-fired furnaces in the West Midlands as early as the fourteenth century, Birmingham’s glass industry was part of the predominantly urban coal-fired glass industry of the seventeenth century onwards.
Birmingham’s first glassworks was
that of the Jewish manufacturer Mayer Oppenheim. Established in 1757 and out of use by 1780/81. The site now lies under Snow Hill Station.
In common with many of the city’s industries the growth of glassmaking followed the development of canals from 1769 when the first canal into Birmingham opened. Canals were ideally suited to carrying the industry’s fuel, raw materials of sand and lime, and its bulky and fragile products. The first canal-based glassworks, Park Glasshouse, opened on the Birmingham Canal in Spring Hill, in 1788.
Chance Brothers of Birmingham
Formerly The British Crown Glass Co. Spon Lane, Smethwick, Birmingham.
Manufacturers of all descriptions of Window Glass, Sheet, Patent Plate, Rolled and Rough Cast Plate, Figured Rolled, Rolled and Double-Rolled Cathedral, Flemish, Muffled, Crown and Coloured Glass.
Established in 1824 when Robert Lucas Chance bought the glassworks.
George Wood assisted Chance in ‘the initial years when the difficulties of furnace construction and the making of special colours and rubies was largely overcome.’ Wood had previously worked for Lloyd & Summerfield of Birmingham and was an experienced colour mixer. His son, Alfred Wood, also worked with Chance as a colour mixer until he departed with his recipes in 1893 to become a partner in Hartley Wood & Co. of Sunderland.
Georges Bontemps was a director of a French glass manufacturer until the second French Revolution. Georges Bontemps fled to England and found employment at Chance Brothers. He was superintendent of the Coloured & Ornamental departments from 1848 until 1854.
The problem of copper ruby was resolved by George Bontemps on behalf of Chance Brothers in 1857, by making one ‘that did not darken when fired in the kiln’. Bontemps was also the first manufacturer in the nineteenth century of a flashed ruby – made in 1826 while he was at the Choisy-le-Roi factory in Paris.” He is attributed with the re-invention of a technique used to make ruby-red glass that was first produced by Venetian glassworkers in the 16th century.
In about 1848 Chance was one of the first companies to produce very long pieces of window glass, following technology developed as a result of finding a solution for an order from Joseph Paxton for a very large greenhouse on the Chatsworth estate of the Dukes of Devonshire.
Chance Brothers also made a great contribution to the ornamental glass industry as a whole in the West Midlands by launching the careers of regional stained glass manufacturers in the region, including Thomas William Camm, who went on to found the Camm Factory in Smethwick. He trained and worked at Chance Brothers from an early age.
In 1850 they had started making dioptric lenses for lighthouses and soon became a major lighthouse engineering company.
“In 1857 the Chance Brothers of Smethwick, surprised when their workers suggested ways of improving production and savings on raw materials, hit upon the idea of putting a wooden box where such ideas could be posted. The scheme proved to be of immense worth to the firm and to the workers. It was also the worlds first suggestion box scheme.”
Chance Brothers and Co bought 14 of the new Siemens regenerative furnace, including a special one for lighthouse lenses. The regenerative gas furnace soon became a financial success from its enormous saving of fuel.
Chance Brothers became the largest British manufacturer of window and plate glass during the mid 19th century, producing the glass used for The Crystal Palace (1851), the Houses of Parliament (1860) as well as ornamental windows for the White House in America. The four faces of the Westminster Clock Tower (Big Ben) were also produced by Chance Bros, the only firm at the time able to make this opal glass.
Chance Brothers & Co. exhibited at The Sydney International Exhibition of 1879.
Clock Tower, Palace of Westminster
The clock faces are set in an iron frame 7m in diameter, supporting 312 pieces of opal glass, rather like a stained-glass window. Some of the glass pieces may be removed for inspection of the hands. The surround of the dials is heavily gilded.
By about 1870, Chance had reached its peak and was employing upwards of 3,000 people. Chance Brothers provided social support for workers and their families, establishing schools, medical care and welfare. Employees were rewarded for initiative and inventiveness with cash bonuses.
In 1913 Chances acquired the Glasgow Plate Glassworks.
A half stake in the company was bought by Pilkington Brothers Ltd in 1945, who completed the buy-out in 1951. The production of flat glass ceased at Smethwick in 1976, ending over 150 years of glass production in the area.
“The Chance family first had contact with glass making with the Nailsea glass works at Bristol. Robert Lucas Chance bought the British Crown Glass Company’s works in Spon Lane, Smethwick in 1824. The company specialised in making crown window glass. The company ran into difficulty and its survival was guaranteed in 1832 by investment from Lucas’s brother William, they became partners in the business, which was renamed Chance Brothers and Company. James Timmins Chance became a partner in 1839.Chance Brothers was amongst the earliest glass works to carry out the cylinder process in Europe making the first British cylinder blown sheet glass using French and Belgian workers. In 1848, under the supervision of Georges Bontemps, a new plant was set up to manufacture crown and flint glass for lighthouse optics, telescopes and cameras. The optical glass work led to the supply of 2300 lighthouse lanterns around the world. Chance Brothers provided the glazing for the Crystal Palace to house the Great Exhibition of 1851, Smethwick neighbour Fox, Henderson and Company having won the contract to supply the ironwork and build Joseph Paxton’s design.Chance Brothers provided social support for workers and their families, establishing schools, medical care and welfare. Employees were rewarded for initiative and inventiveness with cash bonuses.After the publication of the History, the company continued to work on the many new ways of making glass evolved at Chance Brothers such as the innovative welding of a cathode ray tube John Logie Baird used for television; began producing pressed domestic glassware; in 1947 Chance set up plant in Malvern for the manufacture of syringes and precision tubing. Pilkington Brothers acquired a 50% shareholding in 1945 and by 1952 had assumed full financial control, but were not actively involved in its management until the late-1960s. Production of flat glass ceased in 1976, the remainder of the works closed in 1981 ending more than 150 years of glass production at Smethwick.In 1992, during a period of rationalisation at Pilkington, a management buy-out reverted the Chance plant in Malvern to private ownership and it became an independent company, changing its registered name to Chance Glass Limited and retaining the historical Chance logo. The Spon Lane site is the focus of the Chance Glass Works Heritage Trust’s work in rejuvenating the area, conserving the listed buildings, restoring economic activity, promoting cultural and heritage values.” A History of the Firm of Chance Brothers & Co. Glass and Alkali Manufacturers
MAKING GLASS AT CHANCE’S GLASSWORKS: A VISITOR’S ACCOUNT FROM 1852
Chance Brothers: The French Connection – by Rita Bailey
From The Leisure Hour – March 2, 1872.
Chance Glass Works c1871-
The visitor is first conducted to the place where the crucibles are made, in which the sand, soda, and lime — the three chief elements of the whole manufacture — are melted into glass. These crucibles are formed of Stourbridge clay, which is thoroughly kneaded and built up, piece by piece, entirely by hand. The pots thus made are slowly and carefully dried, and, after months of baking, are ready for the stock-shop, where about four or five hundred are generally kept for use, each being worth about £5, and capable of holding some two tons of “metal.” We next come to the glass-house. The great gas furnaces are glowing and roaring, and the workmen passing to and fro before them, thrusting in their long iron blowpipes, on which each gathers a lump of glass and blows it into a globe-like form, which is again and again heated, blown, and worked, till it assumes the shape of a disc or wheel, and is carried away to be annealed, cooled, and cut up into what is then “crown glass.” At other furnaces sheet glass is being made. The manufacture of sheet glass on the continental principle was introduced into this country by Messrs. Chance in 1832, when they secured the valuable co-operation of M. Bontemps, at whose works near Paris they had seen it produced. A better kind of this glass, surpassing even the best foreign, was brought out by Messrs. Chance in 1838: the Crystal Palace was afterwards glazed with it, and it has now superseded “broad” or “spread” glass, the manufacture of which has been abandoned. The sheet glass is blown by the workmen in cylinders, which they lengthen by swinging their rods to and fro, and check from excessive lengthening by reversing in the air, thus giving them the exact regulated size; the cylinder being then opened and expanded, is removed to another furnace, and finally carried off, flattened, and finished. [footnote: By the rectangular shape of this glass, and still more by the absence of the bull’s-eye, a great saving was effected. Panes could be obtained of the full size of the sheets blown, and the only limit to their dimensions was the strength of the workmen. ] A patent plate glass which has been recently introduced is obtained from sheet glass by a new process of grinding and polishing. Many other kinds of glass may also be seen, and we note especially the optical glass. In 1848 M. Bontemps joined Messrs. Chance in an attempt to improve and extend this manufacture. They ultimately succeeded in producing flint and crown discs of twenty-nine inches diameter (which were bought by the French Government for £1,000 each), and discs of twenty-six inches for other large telescopes. On the other hand, they make glass for microscopic uses from the 200th to the 300th of an inch in thickness. But the most remarkable and most interesting part of this gigantic establishment is the lighthouse branch, where those magnificent dioptric lights are made that have attracted so much notice in the International Exhibitions, the upper and lower portions of which are rings of prisms, while the centre is a series of refracting lenses; the whole being of brilliantly-polished glass. The manufacture of these is a wondrous spectacle. To this is devoted an area of nearly an acre and a half, a glass-house for casting, a steam-engine of forty-horse power, about forty newly-contrived machines for grinding with mathematical exactness and polishing the lenses and prisms of all forms; as many lathes, planing, and other machines in the fitting-shops, where lanterns, lamps, clockwork, and all metallic accessories are prepared; and, lastly, a staff of about a hundred workmen. Here Science and Art are indeed united! In the first shop great circular tables, on which the zones of glass are slowly ground and polished, whirl swiftly and incessantly round and round, — in the fitting shops, these zones are fixed into their frames of iron and gun-metal; and then we come to the erecting house where each optical apparatus is tried before being sent off. And “nothing,” says Mr. Alan Stevenson, “can be more beautiful than an entire apparatus for a fixed light of the first order. It consists of a central belt of refractors, forming a hollow cylinder six feet in diameter and thirty inches high; below it are six triangular rings of glass ranged in a cylindrical form, and above, a crown of thirteen rings of glass, forming by their union a hollow cage composed of polished glass, ten feet high and six feet in diameter.” A single lamp is placed in the focus of one of these, and a blaze of light is thrown seaward, which in some cases may be seen at a distance of thirty miles, either as a flash, with intervals of darkness, or as a constant beam. The weight of the unworked cast glass in a complete revolving light of the first order is about two and a quarter tons, and in a complete fixed light about two tons, assuming the prisms to be eighteen and eight in each light respectively. The value of a first-order fixed light with eighteen and eight prisms, with its accessories, is about £1,500; that of a first-order revolving light about £2,000. About a hundred and thirty sea-lights have been constructed by Messrs. Chance for the British Government and for foreign coasts, as well as a large number of harbour lights. Messrs. Chance presented us with a list of dioptric lights constructed by them since 1855, which gives the locality and description of apparatus for 360 of these lights, and includes the coasts of almost every country. Some of the most remarkable are the Whalesey Skerries’ in the Shetland Isles, a revolving light, described as perhaps the most powerful in the world; the Lundy Island light, also revolving, distinguished by the late Royal Commission on Lights as visible at the greatest distance of all the reported lights at home and abroad; the fixed light at the Orme’s Head in North Wales, and the fixed light at Europa Point, Gibraltar. The Wolf Rock Lighthouse, near the Land’s End, and the Souter Point light, near Sunderland, are also fine recent specimens ; the former is a first-class revolving apparatus, showing alternate red and white flashes of equal power; the latter, a revolving light, giving white flashes, and remarkable as having the electric spark instead of an oil flame. It was stated some few years ago that Messrs. Chance had lost more than £20,000 in the manufacture of dioptric lights, which they nevertheless continued to carry on from patriotic motives, and not without the hope of final advantage. They are the only manufacturers of these lights in the United Kingdom, and there are but three others in the world, these being M. Lepaute, M. Sautter, and MM. Barbier and Fenestre, all of Paris. Who can look on these noble instruments without thinking of the dark night and the tempestuous sea, — the ship approaching the coast, the doubt and the dismay which chill the hearts of her officers and crew, — and the splendid outbursting of these friendly lights to guide the mariners safely to the desired haven?
The visitor is finally led to the warehouses, and sees, in a whole mile of store-rooms, stacks of crown and sheet glass, masses of prisms, crates of coloured glass of varying hue. He learns, also, that eighteen hundred and fifty people — men, women, and children — are employed, and from seventy to eighty thousand tons of coal annually consumed in these works, which have been visited by many individuals of distinction in science, art, and literature, and persons of all ranks, from princes downward.
We have alluded to the workpeople. They are well and kindly cared for. A large library and a comfortable reading-room are provided for their recreation, and a surgeon is attached to the works for their aid in sickness. But, more than all, admirable schools, with playground and gymnasium, are established for their children, with day and evening schools for the workpeople of both sexes. We were told that there are about one hundred and fifty teetotallers employed in the works. Some of the workpeople are Frenchmen, the descendants perhaps of those who came to this country of old from Lorraine. Amid all the convulsions of their native land they have here a peaceful home, where they may not only quietly earn their own bread, but daily witness the triumphs of science and art, and see their children growing up in the love of the country that gave them birth, — of the generous employers who not only provide for the good of their workmen, but for the culture and happiness of their workmen’s little ones, — and of those employers’ countrymen, once regarded as natural enemies of France, but now acknowledged to be the very best friends she has in all the world!
“Glass,” says Sebastian Evans, “is at once the Prometheus and the Proteus of fabrics.” How strange that this most brilliant and beautiful substance should be so largely manufactured in the Black Country. It is also an odd coincidence that productions so full of ingenious contrivance and elaborate design should be manufactured by Chance!
Other Glass Producers
Soho and Vesta Glassworks – 1805 in Lodge Road Hockley that became John Walsh, ‘Walsh’s’ works in 1850.
Islington Glassworks in Broad Street (established in 1815)
Aetna glassworks Est in 1836-7, Located on Broad Street where the Hyatt Hotel is now.
Vauxhall glassworks in Lambeth
James Powell and Sons also known as Whitefriars Glass. English glassmakers, leadlighters and stained glass window manufacturers.
Hardman & Co., otherwise John Hardman Trading Co., Ltd., founded 1838, began manufacturing stained glass in 1844 and became one of the world’s leading manufacturers of stained glass and ecclesiastical fittings.
Britten & Gilson of Southwark, London. Maker of stained glass windows.
London and Manchester Plate Glass Co
Birmingham Plate Glass Company
Eccleston Crown Glassworks
Beatson, Clark Glass Manufacturers
Masborough, England (c 1751 to present)
Originally the Rotherham Glass Company, on land belonging to the Earl of Effingham, a crown window glassworks & a bottle and flint house, both run by John Wright & partners. 1783 bought by William Beatson. Specialised in commercial & pharmaceutical glassware, from doorknobs to pill-bottles. In various partnerships existed as a family business (latterly as Beatson, Clark & Co) becoming a public company in 1961. Last hand-blown glass c 1954.
Nailsea Glasshouse, The
near Bristol, England (1788 – 1870)
Founded as The Nailsea Crown Glass & Bottle Manufacturers by William Chance, John Robert Lucas & Edward Homer. Robert Lucas Chance left to acquire The British Crown Glass Co (at the Spon Lane Glassworks) in Birmingham in 1824 (later forming Chance Brothers, which eventually bought out the Nailsea Glasshouse in 1870)
Southwark Glass Works
London, England (1920 – 1928)
Formerly the Abbot Bottle Works. Reginald G Kempton with his father Richard (both from Albert Glass Works) & A H Williams. Moved to Broxbourne, Herts in 1928 & became Nazeing Glass Works Ltd
Buckingham’s Glassworks belonged to the Duke of Buckingham, having been started in 1612 by Sir Edward Zouche. The site of the Buckingham Glassworks looks very similar to the site of the Albert Glass Works, the precursor of the Nazeing Glass Works which also originated in Vauxhall and Kennington.
John Baker’s Glass Works was on the site of the MI6 building and started sometime before 1681. And a third maker was John Bellingham.
INTERNATIONAL IMPORTANT SUPPLIERS
Founded during the reign of Louis XIV, the Royal Manufactory of mirror glass developed a revolutionary procedure that involved casting glass on a metal table. It opened its main production site in a small village in the northeastern part of the Kingdom from which it took its name: Saint-Gobain.
AGC Glass Europe is heir to the long tradition of glassmaking in Belgium dating back more than one hundred years to 1914. It was then that Emile Fourcault introduced the glass drawing process, the world’s first mechanised method for producing glass. This invention revolutionised the glass industry, as until then all window glass had been produced by the ancient glass-blowing method. The glass industry in Belgium flourished, to the extent that by 1945 the country was the largest glass producer in the world. Founded in 1961, Glaverbel (which later became AGC Glass Europe) continued this pioneering role by installing the first float glass plant in continental Europe and gradually expanding into central Europe and Russia.
The first glass factory in the United States was built in Jamestown, Virginia in 1608.
Pittsburgh Plate Glass Company
THE WORSHIPFUL COMPANY OF GLAZIERS
AND PAINTERS OF GLASS
“From the early Middle Ages until changing times in the first quarter of the 19th
century, the Glaziers’ activities were largely taken up in protecting their rights. In our history
there are many references to petitions to the Sovereign and the Lord Mayor objecting to
infringements of our privileges. For example, during the reigns of Elizabeth I and James I, the
pernicious practice, begun by Henry VIII, of granting monopolies in commodities to
favourites, had reached such proportions that the cost of glass rose to a point where only
the rich could afford windows in their houses. A coalition of capitalists led by Isaac Bungard
and John Dynes attempted to corner the whole of the glass trade. Following a spirited fight
against this monopoly by the Glaziers’ Guild, it obtained its first Charter in 1638.
Subsequently Bungard and Dynes motivated by the dictum “If you can’t beat ‘em, join ‘em”
became Liverymen of the Company. Today, they would not have been admitted; our
forefathers were more forgiving.
On receipt of their Charter, the Glaziers proceeded against another antagonist,
impeaching Sir Robert Mansell and his collaborators. The outcome was the proper supply of
good glass and lead at a reasonable price.”
Victorian & Edwardian Glass Distributors & Agents
Cashmore & Co: Bristol: Chance Brothers Agent & Pilkington
Rowe Bros & Co Ltd : Bristol: Pilkington
Hobbs Manufacturing : Canada: Chance
J P O’Shea & C : Montreal, Canada
Henry Brooks & Coy: Australia