March 2026: We are doing major upgrades to code here, please be patient regarding any issues. If any page is not working for a period of hours, please contact us. Thank you.
| Monthly Tech-Tip | Feb 14-15, 2026 - Major Server Upgrade Done | No tracking! No ads! |
Not much. These mugs were exactly the same height before a bisque firing to cone 06. The clay is a porcelain made from kaolin, feldspar and silica.

This picture has its own page with more detail, click here to see it.
Left: Dry mug. Right: Glazed and fired to cone 6. This is Polar Ice porcelain from Plainsman Clays. It is very vitreous and has the highest fired shrinkage of any body they make (14-15% total). This is the highest firing shrinkage you should ever normally encounter with a pottery clay.
| Glossary |
Bisque
Potters and some manufacturers fire ceramic ware twice, once to prepare it for glazing (call bisquit firing) and the second time to melt the glaze onto it. |
| Glossary |
Fired Strength
Ceramics, by their brittle nature, have high compressive strength and unsurpassed surface hardness. Maximum fired strength can come at the expense of various working and fired properties, so testing is needed to reach a balance. |
| Firing Schedules |
Plainsman Electric Bisque Firing Schedule
Three-step to 1832F |
Buy me a coffee and we can talk