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When to Underglaze

Greenware versus Bisqueware

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When should a potter underglaze their pottery? Do you need to wait until the pots have been bisqued, or can you underglaze them as greenware?

A great deal of the answers to these questions lie in what products or supplies you are using. Potter-made slips should be applied while the clay is damp. Potter-made engobes should be applied to bisqueware. However, commercially made underglazes are usually formulated to be able to handle a wider range of shrinkage or lack thereof.

Check Your Underglaze

This ceramic box has underglaze decorations on the outside with a glazed interior.
Photo © 2009 Beth E Peterson
Commercially produced underglazes are usually able to be used on either greenware (generally considered to be bone-dry greenware) or bisqueware. Check the labels of your specific underglaze product for further information.

One advantage of commercial underglazes is that they can also be used both before and after bisqueing. You can begin with an underglaze design on greenware, bisque it, then may add more color or detail with underglazes again before applying the glaze coat.

Advantages to Underglazing Greenware

  • After bisqueing, the underglaze will not lift into the glaze during application, even if you brush glaze on
  • Doing it then allows you to see the close-to-finished design, so you can see if you want to darken color depth or make additions.

Advantages to Underglazing Bisqueware

  • Even heavy or wet applications of underglaze will not harm the clay or dissolve it out from under you, so to speak. This is especially useful if you are using watercolor-style underglazes.
  • You can be a lot rougher with the underglazing process, for example, using underglaze pencils, crayons, or pens. Drawing with a pointed underglaze product will not dent, incise or harm the clay surface.
But, as I said before, the choice is really yours for the underglazes you're using.
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