Oct 22, 2026: We are working on protecting our servers against the PHP2Shell vulnerability recently discovered. Servers were upgraded ahead of schedule on Oct 21. This could cause some issues. Please contact us if you encounter any.
These mugs are Plainsman H443. The cone 10R dolomite matte bamboo glaze on the left (A) has 3.5% rutile and 10% Zircopax added to our base G2571A dolomite matte. The one on the right (B) has the same addition but in a base having less CaO/MgO and much more KNaO. This gives it a craze-prone calculated thermal expansion of 7.9 (vs 6.7 for ours). B also stains badly (as can be seen from the felt marker residue that could not be removed using lacquer thinner). Why does A stain only slightly? It has an additional 4% Gerstley Borate, a powerful flux that develops the glass surface better (giving a slightly less matte surface).
| Troubles |
Staining of Fired Ceramic Glazes
Ceramic glazes are glass. That means they are always easy to clean, right? Wrong - because the surface is not always glassy. |
| Recipes |
GR10-J1 - Ravenscrag Cone 10R Bamboo Matte
Plainsman Cone 10R Ravenscrag Slip based glaze. It can be found among others at http://ravenscrag.com. |
| Recipes |
G2571A - Cone 10 Silky Dolomite Matte glaze
A cone 10R dolomite matte having a pleasant silky surface, it does not cutlery mark, stain or craze on common bodies |
| Glossary |
Bamboo Glaze
A high temperature reduction glaze made by adding a small amount of iron oxide to a magnesia matte base glaze |
![]() PayPal | No tracking, No ads, No paywall, No transient content! Just organized, concise information constantly updated and improved. Was this helpful? Consider supporting me. |
Buy me a coffee and we can talk