
Underglaze is a method of decorating ceramic articles, the decoration is applied to the surface before it is glazed. Because the glaze will subsequently cover it such decoration is completely durable, but because the subsequent glost firing is at a higher temperature than used in on-glaze decoration the range of available colours is more limited. ...
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http://en.wikipedia.org/wiki/Underglaze

• (a.) Applied under the glaze, that is, before the glaze, that is, before the glaze is put on; fitted to be so applied; -- said of colors in porcelain painting.
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http://thinkexist.com/dictionary/meaning/underglaze/

Design or colours applied, cut or incised into a ceramic body before glazing and firing. See high temperature colours.
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http://www.encyclo.co.uk/visitor-contributions.php

Decorative colours applied to ware before the application of glaze.
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https://walkerceramics.com.au/resources/glossary-of-ceramic-terms/

Usually refers to pigments, applied to raw or bisqued clay, that are normally covered with a glaze, such as commercial liquid underglazes like AMACO, chalks/crayons, and pencils. May also describe the technique of application of pigments such as washes.
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https://www.bathpotters.co.uk/helpful-guides/94-pottery-glossary

Decoration applied to pots which are subsequently glazed with a transparent glaze. Underglaze colours are protected from wear by the glaze layer on top of them.
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https://www.cromartiehobbycraft.co.uk/AdditionalDepartments/Footer-Content/

Colour applied to greenware or bisque before covering with a transparent glaze.
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https://www.hot-clay.com/clay-glossary
No exact match found.