COLOUR IN GLASS

Rotorua Morning Post, Volume 2, Issue 528, 11 May 1933, Page 3

COLOUR IN GLASS

HOW 0'XIDES OF METALS PRODUCE LOVELY SHADES. Glass is coloured by fusing with it the oxides of different metals. The rich blue colour, seen in smelling bottles and other ornamental _ glass articles, is given by the oxide of cobalt. o great is the colouring power of this material that as much as will lie on a sixpenny piece will give a distinctly blue tnge to a ton of molten glass. The fine canary colour occasionally seen in glass is _due to the presence of oxide of uranium. Ruhy colour is; produced by oxide of gold; the finest amber colour hy oxide of silver; while pale blue, green, and a deep red are the result^ of different exides of copper. Coloured glass is lmown as "fiashed" or "pot" metal. In the former case a film of coloured glass is laid over a greater thickness of white; in the latter, the colour is stirred with the metal in the pot, imbuing its whole substance. Glass exposed for many years to the action of the weather often hecomes covered hy a film showing the colours of the rainbow or soap bubble. 'This is due to partial exidation of the materials of which the glass is composed. A similar effect is produced artifically in the preparation of what is termed "irricfescent glass."