Technology & Medicine › Ancient world › Bronze metallurgy (the Bronze Age)
Glassmaking
c. 2500 BC (Mesopotamia); glassblowing c. 50 BC· Invention or discovery· Tools, energy & materials
Mostly agreedGood evidence; some details, dates or numbers uncertain.
Melting sand with plant ash or soda into glass, first for beads, later for vessels and windows.
See it on the Technology & Medicine map →How it works
Glass forms when silica sand is melted with a flux, such as plant ash or natron (a natural soda), that lowers its melting point. The first glass objects, beads from Mesopotamia, date to about 2500 BC, after glazed ceramics called faience. Vessels followed by about 1500 BC in Mesopotamia and Egypt, made by winding hot glass around a core. Glassblowing, invented in the Levant around 50 BC, made glass cheap, and Romans spread it widely, even into window panes.
Why it mattered
Glass led to lenses, eyeglasses, telescopes, microscopes, laboratory flasks, light bulbs and fiber optics, many of the key tools of later science.
How we know
Glass beads from Mesopotamian sites; cuneiform glass recipes, the best known from Ashurbanipal's library about 650 BC; glassblowing waste from first-century BC Jerusalem; chemical analysis of ancient glass.
Still unknown or debated
Whether glass was first made on purpose or as a by-product of metalworking or glazing is unknown; Pliny's tale of sailors' cooking fire is a legend.
Inside this (1)
Connections (3)
▸Pottery shared kiln skills with GlassmakingMostly agreed
The connection
Glass grew out of the hot-material crafts. Potters learned to glaze surfaces and to make faience, a glazed quartz paste using the same sand and flux as glass. Their kilns and skill at controlling firing gave early glassmakers the know-how and equipment to melt glass.
When and how
Mesopotamia and Egypt; faience from about 4000 BC or earlier, glass beads by about 2500 BC.
How sure are we?
Faience and early glass share ingredients, and Mesopotamian glass recipes describe kiln-style furnaces and firing steps familiar from pottery.
Debates and open questions
Some scholars credit metalworking, whose slag can be glassy, rather than pottery glazing as glass's main ancestor.
▸Glassmaking enclosed the glowing filament of the Incandescent light bulbWell documented
The connection
A hot filament burns up in air, so it must sit in a sealed vacuum. Glassblowers made the bulbs, and platinum lead-in wires were used because they expand with heat at nearly the same rate as glass, keeping the seal tight. Corning's 1926 'ribbon machine' later made bulbs by the millions.
When and how
Menlo Park, New Jersey, 1879, where Edison's glassblower Ludwig Boehm made the bulbs; Swan's bulbs in Newcastle, England; Corning Glass Works in New York supplied Edison from 1880.
How we know
The Edison Papers document Boehm's bulb-making at Menlo Park; Corning's company records cover its bulb contracts and the ribbon machine.
Debates and open questions
Little is debated; the main question is how much the breakthrough owed to better vacuum pumps, such as Hermann Sprengel's mercury pump, rather than to the glass itself.
▸Glassmaking supplied the clear glass for EyeglassesWell documented
The connection
Eyeglass lenses were ground and polished from clear glass, or sometimes rock crystal. Venice's glassmakers produced unusually clear glass by the late 1200s, and their guild soon regulated lens-making. Without clear, bubble-free glass, reading lenses would have been too cloudy to help.
When and how
Venice and Murano, and Pisa and Florence, in northern Italy, in the 1280s–1300s; Venice moved its glass furnaces to Murano island in 1291.
How we know
Venetian guild rules of about 1300 mention glass 'discs for the eyes' and ban selling glass lenses as rock crystal.
Debates and open questions
Whether the first lenses were glass or rock crystal, and whether they were first ground in Pisa or Venice, is not settled.