Method of manufacturing building elements from so-called foamed ceramics

Claim 1

In the method of manufacturing a block-like foamed ceramic building element in a mould of refractory material which comprises: (a) coating at least the bottom surface of the mould with a layer of a glass material or a glass-forming composition having a melting point of 800°-1000° C. and being non-expandable when heated, (b) charging an expandable ceramic composition into the mould, said expandable ceramic composition being capable of forming a foamed ceramic when heated to a temperature between 800° and 1100° C., (c) heating the mould and its contents to temperatures between 800° and 1000° C. for a period of time sufficient for the foamed ceramic and the glass to fuse together at their interface, the improvement which comprises (1) said glass material or glass-forming composition being uncolored and free from substances which will cause coloring when the glass material or glass-forming composition is melted, said glass material or glass-forming composition being in the form of crushed particles, and (2) prior to charging the expandable mass to the mould placing on the layer of glass material or glass forming compositions a carrier sheet, said carrier sheet being composed of meltable or destructible material, carrying a layer of pigmented color glazing material, (3) said heating of the mould being carried out under oxidizing conditions to foam the ceramic and to fuse together the glass, whereby, after the expandable mass has expanded and the glass material or the glass-forming composition has been sintered and said carrier sheet has been melted or destroyed, the pigmented glaze layer appears as a colored background through the uncolored sintered glass layer.