Fig. 109.—Airostyle Plant Installed for the Gas Light and Coke Co., Ltd., showing Hood in Greater Detail and a Meter with Masks Affixed.
Safe Baking Heats of Pigment Colours.
All colours are more or less affected by heat. They lose their brilliancy, become very much darker and sometimes turn black when baked at too high a heat.
Prolonged heat (not too high) kills the elasticity of the enamel. It does not affect the colour.
To assure brilliancy of the colour, the following highest heats can be used with safety.
| White | 160° | 4 | hours. |
| Pale Blue | 175° | 2-3 | " |
| Pale Gray | " | " | " |
| Pale Green | " | " | " |
| Pale Yellow | " | " | " |
| Gray | 200°-225° | 4-3 | hours |
| Bright Red | " | " | " |
| Green | " | " | " |
| Yellow | " | " | " |
| Dark Blue | " | " | " |
| Olive Green | 240°-275° | 4-3 | hours |
| Maroon | " | " | " |
| Brown | " | " | " |
| Black - any heat up to 600° |
Comments on the Above.
A well-known English firm, commenting on the above says:—
"Generally speaking, the information given therein is quite correct, though it should be remembered that instruction as to stoving temperatures which might be quite correct with one maker's materials, might be quite wrong with another's.