Ingredient Amount
OM 4 Ball Clay 975.60
Sodium Hexametaphosphate 24.40
Add Amount
Water 8.00


I mix these terra sigillata recipes in 1000 gram batches, which require 8 cups of water. To make the mixing easier, I use wide mouth gallon jugs, and prefer glass so it is easier to see whether the layers have separated.

This is a great flashing sigillata, from warm red to dark brown. For different colors add the following amount of stain to one cup of terra sigillata: 40 grams Mason stain 6600 Best Black; 60 grams Mason stain 6242 Bermuda; or 40 grams Mason stain 6131 Iron Titanium Brown Spinel.

Making Terra Sigillatas

Mix deflocculent (I use sodium hexametaphosphate, a fabric water softener from the Dharma Trading Company) in warm water, preferably in a blender, pour into a container with correct quantity of water and add dry materials. After sieving, ball mill the terra sigillata 6–8 hours to increase the amount produced in a measured batch and reduce waste. After ball milling, let the terra sigillata settle for a week or more in a clear container, ladle off the clear water layer on top, then pour off the middle layer of terra sigillata. A layer of larger clay particles will have settled on the bottom of the container.

This recipe was shared by Alan Willoughby in the April 2019 issue of Ceramics Monthly.