Casing of Colourless by Cobalt Blue Glass. Part II. The Question of Setting Rate

JSGT V12 T075-T085

 When the glasses were prepared and drawn out into rod form it was quickly noticed that there was a difference in working properties between the colourless glass and those containing cobalt oxide. The difference was enhanced as the amount of cobalt oxide was increased, the general effect being a diminution of the working range, a quicker setting at the end of the drawing process, a more pronounced chilling of the parison when it was rolled on the marver, and a greater capacity for reheating (in the sense that the reheating took place more quickly) when the parison was warmed in the mouth of the furnace.

S. English & W. E. S. Turner