Basic Terra Sigillata Formula

1 liter water

400 grams clay

4 grams soda ash

Judith Motzkin Terra Sigillata


14 C Water

7.5 grams Deflocculant (calgonite, soda ash, sodium silicate, sodium hexametaphosphate)

1080 grams OM#4 Ball Clay

60 grams Bentonite

260 grams EPK

Dissolve deflocculant in the water.

Dry mix bentonite with other clay to avoid bentonite clumps.

Sift clay into water.

Allow to slake, fully wetting the clay, before mixing.

Mix then pass through a fine sieve.

Let settle undisturbed for 22 hours.

Siphon off the top third or until you reach the visible separation point.



Add 7% of these minerals for colors:

Iron=rose red

Copper carb= warm grey\

Cobalt carb=blue


Or experiment with Mason Stains of your choice.
Ball milling, while not necessary, will give you more and finer slip.