Glass Casting

Gold Star Crystalcast

Gold Star Crystalcast is a plaster-bonded investment powder specifically designed for casting glass. The refractory content and permeability of Crystalcast enables firing cycles to temperatures as high as 900°C for as long as 10 days depending on the mould size.

To enable the removal of filigree work from the mould without breakage and for ease of use, Crystalcast has been designed to have high strength during firing, yet removal from the cast item when cool is very easily achieved, limiting any chance of damage.

Crystalcast has been formulated with a high-technology particle size distribution ensuring that every detail of the mould is reproduced with an exceptional surface finish. Gold Star has optimised the strength of this investment powder so that it permits the casting of small or large sculptures.

Crystalcast is mixed using the same method as a standard plaster-bonded investment, with a water to powder ratio of 32:100. After the mould has cured for a minimum of three hours, the pattern is then removed by the steam de-wax process. This process can take up to 4 hours but is dependent on mould size. Care must be taken not to steam de-wax the mould for too long as it can cause damage to the mould surface.

The de-waxed mould filled with glass crystals is placed in a cold oven and fired as per graph. The furnace should be ramped up at no greater than 50°C per hour until a temperature of 850°C is achieved, this temperature is to be held for around 30 hours; the length of time is dependant on its size. When the glass becomes molten it flows under gravity into the voids of the mould completing the casting process.

The mould must be cooled in the furnace at a rate of no greater than 10°C per hour to ambient temperature. At this point the casting can be gently removed; never quench glass or crystal castings.