MIKE BAILEY

摘要

This article carries on from the one in Ceramic Review issue 229, which described how glazes can be tested by altering one variable (a progression test) or two variables (a line blend) or three variables (a triaxial), with the testing of four and five variables. Tests based on four variables are known as quadraxials and pentaxials for testing five variables. There are several systems for conducting these types of test but the particular method used here is based on the idea of giving glazes a position on a graph. This gives a clear picture about how the matt, crystalline and transparent glazes are produced from the balance, and just as importantly the imbalance, of the fluxes with the alumina and the silica. In this example, to explore cone 8/9 stoneware glazes, the four glazes chosen (A,B,C and D) are plotted on the graph (image 1). These are on the 'corners' of the 5 X 5 grid that will be used to make a set of 25 tests and the resulting recipes and their simplified percentage analysis are given in table 1. In the simplified analysis the fluxes, mainly calcium, magnesium, potassium and sodium oxides are added together and it is the percent weight of alumina and the percent weight of silica that are used to plot each glaze as a point on the graph.