The Coloration of Glass by Staining. Part III

JSGT_1936_V20_T225_T244

The tint and intensity of the colour of glasses stained by silver were measured by the transmissions of the glasses for red, yellow, green, and blue light. The formation of the colour of silver-stained glasses proceeded by progressive absorption of the blue, then the green, the red being transmitted almost completely. Batch additions favourable to colour formation were: As₂O₃, Sb₂O₃, SnO, CdS, FeO, NaCl, and Ce₂O₃; a mixture of As₂O₃ and KNO₃ was very favourable, but alone, the action of nitrates and selenium was very unfavourable. The effects of MnO, (NH₄)₂2SO₄, Na₂SO₄+C, fluorides and cryolite, were either weak or variable. The part played by the major glass constituents was less clear. Experiments on copper staining enabled the relative influences of the stabilising oxides to be determined. The varied colorations obtained could be explained by the existence of copper in the glass in four distinct states, the equilibria of which are extremely sensitive and difficult of study.

P. Gilard & L. Dubrul