Terra Sigillata is a Greek term meaning “earth seal” or “seal of the earth”. It consists of the finest particles of any clay or clay mixture.
I recommend using a large, clear jar in order to see the layers of the sig. First, mix deflocculant into warm water, then sift in the clay. Let it sit undisturbed for about 24 hours. The heavy particles sink to the bottom and the lighter particles rise to the top. The sig is the middle layer. I use a turkey baister or cup to remove the sig from the jar. Discard sludge from the bottom. This recipe produces little or no water.
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)
Start with a white base and add stains or oxides to create a palette of your own. You can add more than one stain to the white sig base. The combinations are endless.
I use 1 tsp. of stain to 1/2 cup of sig. The color and sheen of the sig will be affected by the end firing temperature.
*use additional zircopax to achieve a “true white”
Apply sig to wares at the bone dry state. Brush three very thin coats with a soft moppy brush. For a soft sheen, burnish the sig with a veggie bag before it completely dries. Work in small sections around the piece.