Glass History
A rough outline, notes & links

Rev. 2002-06-01; 2003-01-08, 2004-04-05, 2005-08-19, 2006-05-17,
2007-03-18, -03-26, -11-05, -11-27, -12-02

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Heaven forefend that I present myself as a glass history expert. A site with a lot of history info is at the Corning Museum of Glass http://www.cmog.org/ and the Rakow Library at the same location is a valuable resource for tough questions  http://rakow.cmog.org [should work]  Bibliography
Tangram Technology Ltd. - Glass Timeline has another time line.

The history of glass can be divided roughly as follows

Not man-made

Natives in many countries used obsidian which is a usually black volcanic glass that will hold an extremely sharp edge and thus is good for knives, scrapers, and arrow and spear points while being brittle and fragile. Chunks of obsidian were trade objects and tribes of hunters returned to good sites to make points, leaving piles of scrap behind.   Glass is also made when lightning strikes certain kinds of sand, but it is a curiosity since it is a rough tube and normally can not be melted for reuse because it is nearly pure quartz with a high melting point. 2007-12-02
 

Really, really old stuff (2500 BC - 200 BC)

The period when people are doing a lot of guessing, like how glass was discovered, much glass was made, and who did what. Unlike some other discoveries made in several or many places, it is possible that actually making glass from chemicals (as opposed to melting chunks of broken glass and using it) may have been discovered in one place (Mesopotamia) and retained as a tightly held secret for centuries, which is contended by one author.
In this time frame we have glass used like gem stones [2500 BC Mesopotamia]* and glass vessels made by pulling threads around a clay core or by rolling clay in broken glass, melting it to form a surface and then threading glass for decoration over the melt. [core-forming, 1550 BC, Mesopotamia]  For a discussion of glass pottery where glass material from metal smelting was pushed around by pottery people, see here. [2007-12-02]  Probably nothing blown. [Egyptian core-formed c.1380 BC] [Fused mosaic slumped over form, 15th C.BC Meso.] [Vessel glass gone, 1200-900BC Meso. hiatus 1070-600 BC Egypt] [8th C.BC Mosiac production leads to vessel production, lost wax casting, Phoenician]
* [bracketed dates are from GLVAM]

2500 BC	Cast glass to work like gemstone beads	Mesopotamia	GLVAM
1550 BC	Core formed vessels	Mesopotamia	GLVAM
15th c	"Massive cutting & lathe turning from blocks"	Egypt	GLSMI
14th c	Mosaic fused and slumped vessels	Mesopotamia	GLVAM
1380 BC	Core formed vessels made locally	Egypt
700-799 BC	Mosaic, vessels, lost wax casting	Phoenicia	GLVAM
100 BC	Roman Empire & blown glass develop	Roman Emp.	GLSMI

Really old stuff (27 BC - 400 AD)

This is the time when Rome was using a lot of glass vessels, [pillar molded by slumping, Roman] which combined with the way the stuff holds up means there is a lot of old Roman period glass still around. Somewhere in here [Augustus, 27BC-14AD, blowing] it is felt that someone discovered glassblowing, possibly by using a fired clay tube in a wooden tube holder [although clay tubes have not been found, so probably metal.] [blown the norm by 50 AD] This is also when pressed glass objects like medallions were made and some really incredible pieces (cage cups) where much glass was removed from a thick walled vessel, leaving a net or cage of glass around a thinner inner cup. [Glassmakers mentioned in Lyons (Gaul), Athens (Greece) Mauretania (Morocco), Dalmatia, and Cologne (Rhineland) c.100AD] [40AD mold blown glass] [70 AD intentionally decolorized glass]
http://www.romanglassmakers.co.uk/index.htm Roman era glass melting reconstruction.

c.10 BC	Blown glass	Roman - Augustus emperor
50 AD	Blown the norm	Roman
100 AD	Glass makers wide spread
c 400 AD	Roman Empire collapses
c 450 AD	Glass houses in Kent	Angles & Saxons.
610 AD	Rise of Islam	Mecca - Arabs
732 AD	Moors stopped in S.France
9th Cent	Potash replaces soda in glass - move to woods
to 11th Cent	Rise of Islamic glass on roots in Egypt, Syria & Iran.	Molds, cut glass, surface painting
11th Cent	Glass production in monasteries	Benedictine, Monte Cassino, IT
800-1400	Rise of Christianity, no glass in burial sites
1173-1271	Venice regulates glass trade-guild rules published
1291	New glasshouses restricted to Murano	Italy	GLSMI
fr. 12th Cent	Rise of enameled decoration in Islamic
to 13th	Rise of forest glasshouses in northern Europe
1450ff	Cristallo - flint pebbles & imported purified soda	Venice (durability lowered, no lime)fs
15th Cent.	Islamic Glass industries dies out.
1527	Patent for filigree glass cane	Serena bros. Venice.

Confused times (400 AD - ?)

As the Roman Empire shifted and collapsed, glass workers were confined to limited areas and escaped to be confined in other areas by people who really wanted to control their talents. Glass making developed in Italy and what is now Germany and Eastern Europe. Toward the end of the period, movement of specific individuals can be tracked as glass of particular features is made in particular places. The image at the right, taken from Didderot's famous Encyclopedia shows one form of furnace factory. Usually this form was contained inside another building which provided shelter for the workers and flue/chimney support for the fires giving the heat. Where is that for this picture? Next floor down.

Fritting the glass

  "The ashes contained more potash than soda and gave a good-quality glass, though discoloured by metallic impurities.
  Attempt to purify the ashes, by boiling with water, filtering off the insoluble residue and evaporating to reclaim the alkali, were only partially successful as the important calcium salts were depleted.  This resulted in a less stable glass.  At the end of the seventeenth century Continental glassmakers successfully produced a fine, colourless potash glass known as 'chalkglass' by adding both calcium compounds and purified ash to the 'batch' - the mixture of ingredients.
  However, even purified ash was contaminated with sodium and potassium chlorides.  In making both soda and potash glass they were removed by preheating the batch for up to 48 hours at 700°C in a special furnace called the 'calcar' to form 'frit'.  Frit is a crude granular form of glass.  The unwanted chlorides could be leached out with water before it was dried ready for the melting-pot.  The development of more efficient furnaces made it possible to transfer the hot frit straight from the calcar to the melting-pot: the chlorides rose to the surface of the molten glass and fused to form a scum, known as 'gall' or 'sandiver', that could be ladled off."  Antiques, p.62 2004-02-28

Move away from Wood

Up until about the time of the American Revolutionary War, the primary fuel for glassblowing was wood or charcoal made from wood. Owning a glassblowing factory also meant owning the owning a fair amount of woodland and hiring woodcutters. In England, this process got banned partly because the Navy needed large supplies of wood for shipbuilding and tall straight trees for masts (guess what country was good for these?)  In other countries, they simply ran out of wood. Burning coal for glass melting requires a change of pot shape and putting lids on pots to keep the ash and cinders out, especially if clear crystal is desired. (Britain also did nasty things to its glass industry with taxes on windows and tariffs on glass.)

From 1750 to 1900

This is the period of great glass making of certain kinds, the hand production of window glass and bottles and the gradual take over of mechanical methods, first for bottles, then for window glass. After the Civil War to the turn of the century was perhaps the greatest period of hand production of glass, yet by the end of World War I, all hand blowers of glass bottles and virtually all window glass blowers were unemployed because of machine development.

Making Glass in America

	Although glass is legendary as the first industry in England's American colonies, at Jamestown, in fact very little if any was produced there and certainly none was commercially returned to England. Glass making seems to have worked hard at being as far behind the frontier as possible. In brief summary, glass factories developed on the far east coast, around Boston and down toward Cape Cod before and after the Revolutionary War. Although other places developed, largely around large holdings of wood, in Vermont and New York, the next big hiccup of development was in the Philadelphia area and into New Jersey which had good sands and lots of wood. Good sources of information are NEGG and GGNG. These factories burned wood and a requirement of running one was ownership of sufficient wooded land to supply the factory for years. One ad cited calls for people to cut 700 cords of wood. [each being 128 cu.ft., one web site giving 15.6 million Btu per cord for Eastern White Pine and 29.1 MBtu/cord for White Oak] Factories had wood drying kilns as part of their setup. Tall chimneys provided a strong draft for the fires. With the development of natural gas as a heat source, people from declining factories in Boston leaped to develop operations the descendents of which are still running operations in northern Ohio (Libby-Owens-Ford) and western Pennsylvania (Pittsburgh Plate Glass PPG). The bottle making and sheet glass manufacturing industries were developed there as Michael Owens (Owens Bottling) developed solutions. With these solutions, the manually blown bottle and sheet glass workers vanished, replaced by workers handling machines and not glass. Today there are glass factories across the country wherever some combination of power availability, supplies, and need merge for economic advantage. Notes on British glass development

FACTORY GLASS

This seems a good point to discuss how glass has been melted/made down through the years. Here I am speculating a lot because I haven't seen good descriptions in several cases. If I cite a source, then someone looked into it.
At some point in history, glass stopped being melted by single artisans in small pots and started being melted in hundreds of pounds quantities with lots of people working together. We have pictures of various operations down through the years, many of them from DIDEROT and his Encyclopedia of mechanical arts of his time.
Using a source that cites a fair number of details, NEGG, early New England glass (1755, p.44ff) was building a furnace that held 6 pots in the furnace, four men working these pots, which will make 300 rolls of glass, each yielding 450 square feet of glass (a pot elsewhere described as making 80-90 bottles, vs 50 window cylinders here.) Unfortunately, the only clue to weight of glass per pot is citing 36.5 pounds of kelp per pot and I am not yet ready to work back through kelp to potash to glass. However, if the glass is 1/8" thick, 75 square feet (50 rolls) yields 117 pounds (at 0.087 lb/cu.in) and if there is 100% waste on production for the tops and bottoms, the pots are about 230 pounds or 1.5 cu.ft. inside which might be 20D x 20"high. Elsewhere, a letter from Ben Franklin states a glass furnace is 12 foot long, 8 wide and 6 high the fire being laid on the floor and the pots "3 or 4 on a side" stand on a clay bench. If these are outside dimensions with walls 6" thick, 4 pots would be about 7 feet with no spacing between, leaving 4 feet to spread the pots or to provide arch support for the roof and leave an opening to remove the pot.

UTILITY GLASS

The making of ordinary glass for ordinary uses, rather than art glass for rich patrons or ceremonial uses seems to have really risen in the mid 18th century and progressed to the beginning of the 20th when mechanical methods for blowing glass settled in, removing the human lungs from the equation. The changes since then have mostly been in window glass production rather than bottles or glasses.
During the 19th century, massive amounts of glass were hand formed with increasing amounts of hardware to assist.

Blown Molded

Blown glass can be shaped entirely by hand, but for production, it is often best to have a head start on the shape by blowing into a mold, which may provide the entire shape of the final product (say a log cabin shaped bottle for a brand of bitters) or only provide the initial working shape, say a textured base globe base below a cylinder neck, which is then worked by the gaffer to be a decanter, or a pitcher or a lamp. Molds are usually iron, but can be brass, wood or aluminum (today)

Pressed glass

If a mold is made for the outside of the glass and a shape is made to form the inside or top of the glass and these two are mounted so a lever will press the latter into the former, then pressed glass is made when a gob of glass is put in the mold and pressed. After the pressed glass is taken from the mold, several things can happen: it can be annealed as pressed, it can have handles and/or a foot attached, it can be further formed, as say a lip on a pitcher, it can be used as a foot or other hot bit for a blown piece.
What makes pressed glass important in history is that it allowed mass production, particularly of bowls that looked like cut glass, but without the manual labor of cutting.

Mechanical glass

Untouched by human hands, glass made entirely by mechanical processes is tricky to set up and a lot of money was spent on trials and failures before Michael Owens, among others, made things work. The critical problem is that very hot glass must be exactly measured (usually by holding the temperature correctly and letting it flow through a hole until cut off) and then manipulated for shaping and blowing without cooling it too much or damaging the iron molds needed to stand up to production. Bottles, glasses, and sheets are made mechanically. The glass is usually a formula with a narrow soft range (short glass) so that once it hits the mold it gets hard quickly and can be released from the mold. Typically the gob is dropped into a shape and a plunger both preforms it and applies air to blow the glass down into a mold. 1226 BROAD SHEET was first made in Sussex, but of poor quality, and fairly opaque. Manufacture slowly decreased and ceased by the early 16th Century.

1226	BROAD SHEET was first made in Sussex, but of poor quality, and fairly opaque. Manufacture slowly decreased and ceased by the early 16th Century.	England	LCGCH
1330	French glassmakers produced CROWN GLASS for the first time at Rouen. Some French Crown and Broad Sheet was imported into the UK.	France	LCGCH
1615	Coal used for melting glass, patent issued, wood banned	England	GLVAM
1620	BLOWN PLATE was produced in London by grinding and polishing Broad Sheet,	England	LCGCH
1688	Casting large sheets of plate glass for mirrors	France	GLVAM
1730	Lead crystal - potash & lead oxide, no lime, no soda	England	GLVAM
1773	English POLISHED PLATE by the French process was produced at Ravenshead	England	LCGCH
1780-1810	English cut crystal peak	England	GLVAM
1790
1810-	Three piece mold blown forms for tableware		GLVAM
	Pressed Glass		GLVAM
1834	Robert Lucas Chance introduced IMPROVED CYLINDER SHEET, using a German process	England	LCGCH
1870-	Peak for American Cut Crystal	USA	GLVAM
	Michael Owen bottle blowing mechanization		GLVAM
1900	Collapse of the handblown glass industry with intro of machines.		MF
1959	Float glass for windows, cooling on molten tin	England	MF

LCGCH - The London Crown Glass Company - The History of Glass

2500BC	2000	1500	1000	500	400	300	200	100 BC	100 AD	200	300	400	500	600	700	800	900	1000
2500 BC Cast glass to work like gemstone beads Mesopotamia GLVAM
	1550 BC Core formed vessels Mesopotamia  GLVAM
		15th c "Massive cutting & lathe turning from blocks" Egypt GLSMI 14th c Mosaic fused and slumped vessels Mesopotamia GLVAM 1380 BC Core formed vessels made locally Egypt														9th Cent Potash replaces soda in glass - move to woods		11th Cent Rise of Islamic glass on roots in  Egypt, Syria & Iran. Molds, cut glass, surface painting
			700-799 BC Mosaic, vessels, lost wax casting Phoenicia GLVAM					100 BC Roman Empire & blown glass develop Roman Emp. GLSMI c.10 BC Blown glass begins Roman - Augustus emperor						610 AD Rise of Islam Mecca - Arabs				11th Cent Glass production in monasteries Benedictine, Monte Cassino, IT
									100 AD Glass makers wide spread			400 AD Roman Empire collapses			732 AD Moors stopped in S.France
									50 AD Blown the norm Roman			c 450 AD Glass houses in Kent Angles & Saxons.				800-1400 Rise of Christianity, no glass in burial sites

Victorian Art Glass movement

Around the turn of the 19th century (1880-1910), there was an enormous reaction to the busyness of Victorian cut glass, with a number of famous people turning out glass for artistic purposes. These included the firms of Tiffany and Steuben (iridized color) and the people Gallé and Lalique who pressed, carved and molded glass for decorative tableware, sculpture and lighting.

Modern Art Glass movement

By the early 1960's very little handblown glass was being produced outside of factories which were melting glass by the ton. The ceramics trained son of a Corning glass worker, Harvey Littleton, and a glass technologist, Dominique Labino worked to make a glass melting furnace that could melt a hundred pounds or two with a formula that was well behaved and produced clear lead free glass. Littleton's training center, the individual rebelliousness of the times, and a new attitude toward glass produced the movement, starting from a conference at the Toledo Museum of Art. At one point in the movement, it was required that show artists sign a statement that the pieces submitted has been entirely by them, with no help, thus completely abandoning the team approach to glassblowing that had gone on for centuries. This was killed off in part by the arrival of Lino Tagliapietra who demonstrated outstanding glass working skill while showing the advantages of the team in making many pieces and by Dale Chihuly learning in Venice and using the team to make his big pieces.

GQ98 GLASS Quarterly #98, Spring 2005 Article "8 Days in Toledo"

SGBC Warmus Studio Glass Bibliography and Chronology claims to have the best bibliography on the art glass movement and I can hardly challenge that. Arranged chronologically with interspersed historical event notes.  Also includes artist reference data for some artists. Last updated in 2003. 2005-08-19

Bibliography - Link to more books

NEGG

New England Glass and Glassmaking, Kenneth M. Wilson, Thomas Y. Crowell Co., NY 1972, "An Old Sturbridge Village Book" ISBN 0- 690-58075-4 Link to reference page

GGNJ

The Glass Gaffers of New Jersey and their creations from 1789 to the present, Adeline Pepper, Charles Scribner's Sons, NY, 1971 , ISBN 684-10459-8 Link to reference page

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