In cooperation with company Tonaso a.s. and Mr. Ing. Vladimír Henych we are trying to develop new formulas to produce molds for glass casting. Its based on mixture of sand, sodium silicates (water glass) and hardening agent on ester – carboxil accid basis. Similar compositions are used in metal foundry, but the problem with glas casting is, that the molds are exposed to high temperature for much longer time, causing the degradation of the material. The develeopment is still in progress.