What changes might adjust texture and / or opacity of a glaze?.

Unit 3 Topic 11
Focus on Raw Materials

Changes which result in movement away from the clear glaze balance would tend to develop texture and increase opacity.

Changes for lowering the maturing temperature could alter the textural quality of the glaze if it was fired to the original temperature. The nature of the changed texture and opacity would depend on the qualities displayed by the original glaze.

If the original glaze was matt and opaque from high levels of Al2O3 and SiO2 then increases in flux or reductions in Al2O3 & SiO2 might result in the glaze being clearer with less texture.

Conversely an already clear and shiny glaze might become more textured with increases in flux or reductions in Al2O3 & SiO2 as a result of their being an overload of flux oxides which might generate crystal development with opacity and texture being increased as a result.

Predicting quality variations resulting from changes to a recipe is made easier if the oxide content of the glaze is quantified. The next unit of study examines a system for analysing the oxide content of a glaze called Seger (or Unity) formulation.

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