This is from Resource on Glass.
Glassmaking Discovered
Little is known about the first attempts to make glass. The Roman historian Pliny attributed it to Phoenician sailors. He recounted how they landed on a beach, propped a cooking pot on some blocks of natron they were carrying as cargo, and made a fire over which to cook a meal. To their surprise, the sand beneath the fire melted and ran in a liquid stream that later cooled and hardened into glass.
That said, no one really knows how glass came to be made. It is thought that the ability to make glass developed over a long period of time from experiments with a mixture of silica-sand (ground quartz pebbles) and an alkali binder fused on the surface. The material called faience had been used for well over a thousand years to make small decorative objects such as beads and amulets.
Although it existed as an ignored, accidental byproduct of copper smelting, true glass probably was first made in western Asia, perhaps Mesopotamia, at least 40 centuries ago. Perhaps early development began with potters firing their wares.
Could the first glass have been colorful, hard, shiny decoration fused to a clay pot's surface in the heat of the furnace? No one knows. It was later discovered that if the material were thick enough, it would stand by itself. Pieces of solid glass could then be ground to shape by grinding it with stones, or sand and water, to produce vessels.
- Phoenicia: area of modern Lebanon
- Natron: an alkali; a natural occuring evaporate form of soda found around the shores of lakes in the Wadi Natroun
- Egypt--used in the mummification process in ancient Egypt
- Mesopotamia: parts of the countries now known as Iraq and Syria
Secret Instructions
As early as 3,300 years ago, secret "instructions" for furnace building and glassmaking in Mesopotamia were written on clay tablets in a cuneiform script. These instructions were copied and recopied over the centuries. Furnace-building instructions from that time period have not been discovered.
Typical instructions for glassmaking follow:
- When you set up the foundation of a good furnace to make glass, you first search in a favorable month for a day of good omen, and only then can you set up the foundation of the furnace. As soon as you have finished building the furnace you go and place Kubu-images there.
- No insider or stranger should enter the building; an unclean person must not even pass in front of the images. You regularly perform libation offerings before them.
- On the day when you plan to make (glass), you make a sheep sacrifice before the Kubu-images (religions statues); you place juniper incense on the incense burner; you pour out a libation (drink honoring a deity) of honey and liquid butter; only then can you make the fire in the hearth of the furnace and place the glass in the furnace.
- The wood that you burn in the hearth of the furnace should be thick, peeled poplar wood, which has no knots, bound together with leather straps, cut in the month of the Abu (July or August). Only this wood should be in the hearth of the furnace.
- The persons whom you allow to come near the furnace have to be clean; only then can you allow them to come to the furnace.
- If you want to produce zagindurû-colored (blue) glass, you finely grind separately, ten minas (about one pound) of immanakku-stone (quartz), fifteen minas of naga-plant ashes, and 1 2/3 minas of 'white plant.' You mix these together. You place the mixture into a cold furnace that has four openings, and you arrange the mixture between its openings. You keep a good and smokeless fire burning....As soon as the mixture glows yellow, you pour it on a kiln fired brick and this is called zukû-glass....
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