Appalachian Center for Craft - Clay Studio

Vince Pitelka, 2007

  Mason Color Works Underglaze Base

This recipe for an opaque white underglaze base has been generously provided by Mason Color Works of Liverpool, Ohio, makers of Mason ceramic coloring stains, the standards of the industry.  This recipe has been in use for decades, and seems to give very good results.  Click on the hyperlink above to access all sorts of information at the Mason Color Works website.  

Components, Measured in Parts:
Base Materials:
F-4 Soda Spar ---- 20
Kaolin ------------- 10
Ball Clay ------------ 5
3124 Frit -----------10
Zircopax* ----------- 5
Underglaze Liquid** ----------- 75

Add:
Stain ---------------40 (Or for a lighter tint, a mixture of stain and Zircopax to total 40 parts)

*Any zircon opacifier will work

**Underglaze Liquid Components:
Non-toxic anti-freeze ---- 10 parts
Water ---------------------- 10 parts
CMC Liquid --------------- 5 parts

To make CMC liquid, stir 30 grams dry CMC in 1 qt. hot water and let it sit for 2 days to break down.  CMC (carboxymethylcellulouse) gum is an organic thickener used in may applications.  It comes dry and must be properly reconstituted with water to get a useable product.  As you can see by the above instructions, a small amount goes a long way - only 30 grams of dry CMC gum to one quart of hot water.  Do not use a higher concentration of CMC gum to water.  

Normal antifreeze is ethylene-glycol and is toxic. Instead, use non-toxic propylene-glycol antifreeze. Such antifreeze is sold in most auto-supply stores, and is much more friendly to the environment, people, and pets. 

The above mixture is designed to allow you to use a brush and paint directly on greenware without your brush dragging.

Note that the recipe above is given in parts, which could be level teaspoons, tablespoons, quarter-cup measures, or cup measures, depending on the quantity you want to make.  At the Craft Center we often use cup measures and make it in a five-gallon bucket.  It keeps well.