Recently, Michael Kent Knutson and I had the opportunity share our art and techniques with the students at Kansas State University Ceramics Department. Professor Amy Santoferraro was gracious and lovely enough to share her Ceramics 1 and Materials and Surface classes with us.
This blog post will serve as a basic tutorial for those classes and be an aid to adding an interesting surface to these pieces.
surface one: painting with fluxed Terra sigillata and colorants:
Ok here are my suggestions. First, let’s make Terra sigillata. It’s easy to do. Terra sig provides a juicy surface that works great as a low fire matte.
The recipe I have used for years is simple:
In a glass or clear plastic jar:
800 gm clay (red art, ball clay, gold art)
8 gm of darvan.
1 gal of water.
I have always dispersed the darvan in a cup of water before adding this to the clay.
agitate this mixture. let sit overnight. siphon off the center and discard the top (water) and bottom (clay).
I use a 1/2 in. vinyl tube that can be purchased by the foot at your local hardare store in the plumbing department.
I like to create 2-3 batches of Sig and then let it dry in a wide container. I use a plastic kids sled for this. They (round ones that look like a trash can lid) are officially called flying saucer sleds. let your sig dry overnight and then dump it into another container. This one should have a lid.
I brush this onto the figures before I bisque them. I find that the sig added to bone dry clay helps future layers adhere.
Bisque slowly to 04-06
Adding additional layers of Sig with Stains and oxides:
Fluxing your sig.
I have experimented with various fluxes to prevent flaking and I have found Soda Ash, Lithiium, and Colemanite to be suitable – there may be more. Test these fluxes to see what works for you. I use a basic volume measurement of 1 t of lithium to about 1/2 cup of Sig.
Soda Ash is best dissolved in hot water and then added to a small amount of Sig. Soda is soluble. It will crystallize. Do not make more than you will use.
Colorants: Mason stains, oxides.
Note: mason stains sometimes require the addition of specific chemicals for them to work. Reds need calcium (whiting), some stains will not work in the presence of Tin etc. Charts are available from your supplier that will provide you this information.
I like to use black copper (brush on, wipe off). It brings out the texture of the clay. Iron and cobalt are nice. Cobalt is hazardous but can yield beautiful results. Never use Manganese or Chromium. Too much of those minerals inside of your body is a bad plan. Practice safe procedures and always wear a mask.
now add layers of terra sigillata plus mason stains at various ratios. I can’t emphasize enough the fact that we are building up layer after layer of stain/underglaze here. It’s essential that sigillata be milky, and built up in two or three successive applications. You might want to try this technique on a test piece that is textured first just to see if you have got the hang of it.
You can’t do enough glaze tests.
After three or four layers of stained sigg, toss the piece in the kiln. Fire 06-012. The lower the fire the brighter the color.
Keep adding fluxed sigg/stain to the work until it looks beautiful. After a few applications you’ll get the hang of how the work will look after gazing as opposed to before.
Your lovely finished figure can be waxed or clear coated. I’ve used paste wax, varnish, and acrylic.