Cast Glass: from
the Glass Encyclopedia

Cast Glass: A short explanation

The techniques for making Cast Glass involve creating a paste from powdered glass and colouring agents and filling a fire-proof mould with this paste then firing it in a furnace to melt the glass.

The technique was known in ancient Rome and Egypt, but in the art nouveau period (very early 1900s) it was called Pate de Verre and developed to a very high artistic level by such French artists as Gabriel Argy-Rousseau, Henry and Jean Cros, Albert Dammouse, Francois Decorchemont, Amalric Walter, Emile Galle and Georges Despret.

These artists put the coloured glass paste into the mould using a paint brush or similar tool, first filling the sections which would eventually stand out in relief. The background of different colours was then added to a thickness of several millimetres and the centre of the mould filled in some way to prevent the paste from slumping. Argy-Rousseau filled the centre with powdered asbestos.

For both cast glass and pate de verre, the filled mould is fired to melt the glass paste and fuse it into a single piece, and then allowed to cool very slowly to anneal the glass.

Some of today's glass artists incorporate computer controls and thermocouples (for measuring high temperatures) in the mould itself, giving them very precise control over the heating and cooling of the glass. These techniques were first developed for making cast glass lenses and mirrors for huge telescopes.

Finally the mould is removed, either by pulling apart the separate pieces or by lifting out the glass object (only possible with certain shapes) or by destroying the mould to release the glass. Further work on the glass, such as polishing or engraving or decorating is then undertaken.

Making cast glass is a slow process requiring a large amount of skilled craftswork. Experience and knowledge is needed to avoid bubbles, cloudiness, and cracking during annealing (cooling). Many cast glass sculptures are solid and quite large. Even a small piece 10cm thick can take a month of carefully controlled cooling to ensure it does not crack, and at 20cm thickness the time required to cool safely will be about four months.

It was not until after the 2nd World War that techniques were developed for making very large sculptures using cast glass. Stanislav Libensky and Jaroslava Brychtova were the leaders in this development, but their work in communist Czechoslovakia was not widely disseminated in the West until the Czech Republic was set up and greater freedom allowed. Methods of working with cast glass were also developed in the USA, notably by Howard Ben Tre, in the UK by Colin Reid and others, and in New Zealand by Ann Robinson. Today cast glass is some of the most magnificent and skilfull glass produced.