Abstract: A water-dispersible mold for making a casting comprises a water-insoluble particulate material, such as foundry sand, a binder which includes polyphosphate chains and/or borate ions, and at least one fine particulate refractory material such as one selected from finely particulate silica, silicates and aluminosilicates. The incorporation of the fine particulate refractory results in improvements in the strength and related properties of the mold, when hot, prior to casting.

Abstract: A water dispersible mould for making a casting, the mould comprising a water-insoluble particulate material-and a binder therefor, the binder including polyphosphate chains and/or borate ions. The invention also provides a process for making a water dispersible mould for making a casting, the process including the steps of: (a) providing a water-insoluble particulate material; (b) combining the particulate material with a binder including polyphosphate chains and/or borate ions, the chains and/or ions being dissolved in water; (c) forming, either during or after step (b), the particulate material and binder mixture into a desired shape; and (d) removing free water from the mixture. The polyphosphate chains may be derived from a water soluble phosphate glass and the borate ions may be derived from a soluble borate glass.