SPEGELEMNE JEMTE FORFARANDE OCH MEDEL FOR DESS FRAMSTELLNING

摘要

Mirror blank, method of producing the same and mould for the production of the mirror blank. The mirror blank includes a front glass (7) and distinguishes itself by a support structure (14) of porous foam glass fused on to the back of the front glass, the surface layer (15) of the support structure showing a smooth surface. The method according to the invention involves that a composition of glass powder and expanding agent is allowed by heat treatment to expand in a closed space in one mould part (1) of the mould. By the expansion pressure the support structure becomes almost smooth in its surface layer (15) while the remaining part of the support structure is porous. The mould which is used for the production of the mirror blank includes two mould parts one of which has a forming surface (8) which is complementary to the form of the front glass and the other (2) of which has a recess (3) which is surrounded by a countersink (6) in which the front glass (7) is placed.