|Monthly Tech-Tip |
|Frit Softening Point||> 1500C (From The Oxide Handbook)|
-Cadmium oxide by itself does not produce color in a glaze, but when used in combination with selenium it gives red. In combination with sulfur it produces yellow (great care is required to maintain the correct slightly reducing atmosphere during firing for the latter).
Frits are made by melting mixes of raw materials, quenching the melt in water, grinding the pebbles into a powder. Frits have chemistries raw materials cannot.
This is a type of stain manufacture that enables the use of metal oxides (like cadmium) under temperature conditions in which they would normally fail.
Cadmium orange colors at wikipedia
|Glaze Color||Cadmium is blended with uranium to produce yellow optical glass and yellow enamels. For example, a yellow stain for enamels can be made with 12% selenium, 64.5% cadmium sulfide, and 23.5% cadmium oxide.|
|Glaze Color||Red enamels are made using cadmium-selenium-sulfur mixes because this combination goes into solution readily during the short firing period (copper compounds are too slow to dissolve). Great care is required to maintain the correct slightly reducing atmosphere during firing. Cadmium zirconium encapsulated stains are also an option where cadmium by itself is not practical or workable.|
|By Tony Hansen|
Follow me on