Feeding on the Body

摘要

Despite all the advice that the clay body on which a glaze is fired will affect the result, the extent of the interaction is difficult to quantify, other than by trying it out. At earthenware temperatures the interaction between body and glaze is minimal in comparison to high temperature wares, where the so called layer of interaction can be extensive. With some ash glazes, for instance, it may be virtually impossible to distinguish between glaze and body, so profound has the reaction between them been. Clearly, the colour of a body is one of the more obvious effects a body will have: as a general rule, the lighter the body, the brighter the glaze. But not all such interactions are so clear-cut, and one of the frustrations of testing glaze recipes is that the result may be different to that expected, not only because of the varying materials - and these can change widely from supplier to supplier and batch to batch - but also the different clay body. While, to some extent, we can estimate how a glaze will turn out from looking at the formula or even the recipe, the reaction between glaze and body is less easily determined. As Parmelee points out in Ceramic Glazes, 'the glaze feeds upon the body', the extent depending on a number of factors. These include the nature and condition of the body, the temperature and duration of the firing, the composition of the glaze, and the thickness of glaze application.