The following is a low tech recipe for a white based terra sigillata
XX Sagger Terra Sig Recipe
Water 3000 grams (equals 12.5 cups)
Ball Clay 1500 grams (I use XX Sagger)
Deflocculant 25 grams (I use sodium silicate)
In a 5-gallon bucket, add deflocculant into pre-measured water. Slowly sift in the clay. Mix with a power drill until clay dissolves into water solution. Mix for about 5 minutes.
You will immediately notice the heavy particles sink to the bottom and the lighter particles rise to the top. This is a good time to stick your hand in the mixture and actually feel the layers. In most recipes, after the required resting time, there are three distinct layers: sludge on the bottom, terra sigillata in the middle, and water on the top. My recipe produces 2 layers with the sludge on the bottom and the terra sigillata on the top.
After 24 hours, I use a small cup to remove the sig from the 5 gallon bucket into a smaller lidded container-this is the white base sig. No syphoning or tubes; it is “low tech” but it works! Discard sludge from the bottom as it is deflocculated and useless.
Making Color Pots
Start with the white base and add stains or oxides to create a palette of your own. You can add multiple stains to the white sig base. The combinations are endless.
Liz’s Color to Terra Sigillata Ratio
Add 1 tsp of stain to 1/2 cup of sig. I have found this to be the highest concentration of stain to base needed. Adding more stain did not change the intensity of the color.
The color and sheen of the terra sigillata will be affected by the end firing temperature. Low fire produces waxy, shiny surfaces. Mid-range and high fire produces more matt to dry surfaces.
I fire to a cool Cone 03.
Application
Apply terra sigillata to bone dry surfaces. Brush three very thin coats with a soft moppy brush. For a soft sheen, I prefer to burnish the terra sigillata with a veggie bag. Work in small sections around the piece. Alternate burnishing tools are soft t-shirts and micro-fiber rags. Burnish pots before terra sigillata completely dries.