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This set shows some typical features of high calcium glazes. In the bottom left quarter (high in fluxes) the glazes are quite runny in this stoneware reduction firing. They exhibit many of the characteristics of wood-ash glazes (also high-calcium), including the rivulets of glaze on a vertical surface called webbing or stringing. The top left quarter (high alumina) glazes show a tendency towards colour-break, breaking to the brownish colour where the glazes are applied thinly. This type of high calcium alumina matt has been exploited for decades in a range of colour-break glazes, especially with colourants iron (earthy red breaking to yellow) and cobalt (blue breaking to yellow). The bottom right quarter (high silica) shows some typical high silica effects: opaque glazes and opalescent blue glazes. The crystals in glaze number 34 seem to be typical of some high calcium glazes; the effect requires low alumina and the right amount of silica.

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