Clay roofing tile prodn. by pressing in mould - wetted with granite and water suspension before each charge

摘要

In clay roofing-tile prodn. by pressing in moulds, esp. steel moulds, subjected to an electric shock with D.C. tension to release the pressed tiles, the mould-nests are coated, esp. by spraying, with a suspension of graphite and water before each clay blank charge. The addn. of alcohol to the graphite-water suspension increases suspension volatility and reduces the drying time of the tiles. Treatment reduces electric shock damage to mould nest surface and increases mould service-life, e.g. by 50%, i.e. to 6 months.