Porous moulds for the ceramic industry - which have better properties than conventional plaster moulds

摘要

Process for making a material for use in mfg. moulds for the ceramic industry, the novelty being: (a) the very dry materials are weighed and mixed; (b) water is added according to the grain size range, nature and porosity of the aggregate; (c) mixing, followed by mechanical agitation to remove bubbles; (d) casting in a master mould; (e) after a defined setting period the casting is removed and dried in an atmos. satd. with water vapour for final drying. The master moulds are pref. made of plaster coated with vanish to make them impermeable, or they can be made of plastic. The casting is pref. heated at 25-40 degrees C after extn. from the master mould. Materials (a) pref. contain a binder which sets rapidly in the presence of water. As compared with the plaster normally used for moulds, this new material is harder, more scratch-resistant, has a higher absorbent power, and is less soluble. The result is that moulds far superior to plaster moulds can be made for only a very small increase in cost.