2, 5, 10 and 15% alumina hydrate added to Ravenscrag Slip

Pure Ravenscrag Slip is glaze-like by itself (thus tolerating the alumina addition while still melting as a glaze). It was applied on a buff stoneware which was then fired at cone 10R (by Kat Valenzuela). This same test was done using equal additions of calcined alumina. The results suggest that the hydrated version is decomposing to yield some of its Al₂O₃, as an oxide, to the glaze melt. By 15% it is matting and producing a silky surface. However crazing also starts at 10%. The more Al₂O₃ added the lower the glaze expansion should be, so why is this happening? It appears that the disassociation is not complete, raw material remains to impose its high expansion.

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Recipes	GR10-A - Pure Ravenscrag Slip Ravenscrag all by itself makes a great cone 10 reduction semi-gloss glaze. It also has great working properties.
Materials	Alumina Hydrate
Materials	Calcined Alumina
Glossary	Matte Glaze Random material mixes that melt well overwhelmingly want to be glossy, creating a matte glaze that is also functional is not an easy task.

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