The relative strength of the main colouring oxides can be seen in image 10 in which the additions of 0.5 percent, 1 percent, 2 percent, 4 percent, 6 percent, 8 percent and 10 percent are aligned in a grid. Cobalt oxide is clearly the most powerful and manganese dioxide the weakest. The tests produced for this article show the colour response for the metal oxides on their own in a transparent glaze. An enormous, almost limitless, range of tints and tones can be produced by blending coloured glazes and various blending systems, as discussed in Ceramic Review issues 229 and 230. For example, cobalt blues can be toned down to blue-greys by adding red iron oxide and manganese dioxide. This article has dealt with transparent coloured glazes and made reference to opacity being created by overloading the glaze; in which case the colours are at full strength. It is possible to obtain lightly coloured opacified glazes and is the subject planned for the next issue.
展开▼
