Ingredients

Ingredient Amount
OM 4 Ball Clay 10.00
Water 20.00
Add Amount
Sodium Silicate 22.70
Mason Stain 6028 3.00
Mason Stain 6450 4.00
Amaco Bright Red Underglaze (V-387) 1.00

Instructions


Note: clay and water amounts are in pounds.

In a 5-gallon bucket, let the clay slake down into the water, then mix well (5–10 minutes or more). Add the sodium silicate and mix again. Set the bucket off the floor about 6 inches and leave covered and undisturbed for 8 hours. Siphon off the center layer of terra sigillata. The ideal specific gravity is 1.15. If it falls below 1.1, leave the terra sigillata uncovered for a while longer or remix in the bucket and let it settle for less time. If it’s above 1.2, add a bit of water to the terra sigillata or remix and let it settle longer. This recipe yields approximately 2 gallons of terra sigillata. Use one cup of the base for each color addition. Generally, I don’t add any more than 3 tablespoons of Mason stain per 1 cup of terra sigillata base. *For red, I use 1 part underglaze to 3 parts base. Note: each stain/colorant will saturate the base at different levels. Work pretty intuitively when testing sigillata colors—add a little of this, try a little of that, and take notes so you can easily reproduce the results.

This recipe was shared by Kari Radasch in the March 2019 issue of Ceramics Monthly.