THE CRAFT OF FIRE

When working in the Crafts, we talk about developing a certain internal placement or attitude having to do with Permanence , Care , and Tone . In the old Notebooks of School (#8), I found some comments which expanded my reflections on these three points, and I thought I'd translate and post them here. Permanence A plan of work to be carried out should be developed before any activity. This plan should not be altered by other works which may be suggested while carrying out the activity. When other possibilities arise, one can take note and develop them in a future plan of work. Working simultaneously in different activities is fine, but all of that should be foreseen in the plan of work for the day. One should not go on to another production before having finished what one started. Care The workspace, tools and equipment should be ready for use for the work to be done. Tools and materials should be classified and ordered. Tools should be put back in their plac...

We did another firing on the weekend, some raku and some not. This was the firing where I was going to test out my new copper carbonate and get some rudimentary colour on my pieces. It turns out I got more colour on my head than my pieces did. J. checking out the burner It was a sunny 17º outside, warmest March 11 on record, and I actually got a slight sunburn. It's what happens when you're bald and the sun hasn't really shone all winter. I prepared a tin saggar with a bisqued piece inside, with wood shavings at the bottom, a layer of salt in the middle, and then sawdust for the rest, and 8 g of CuCO3 sprinkled throughout - experimenting with a reduction environment, and the copper powder and salt all in one tight space. It came out at 750º, dark grey on the bottom, a heavy black line where the salt met the sawdust, and then black above - and that's it. No copper colouring anywhere. I had also painted a small dish with CuCO3 mixed with water, and sudden...

Bless the internet, because it turns out that by entering something like "making copper carbonate" into Google, you get a bunch of hits including YouTube videos with 12-year old kids explaining how you can make  CuCO 3  at home in a few easy steps. Thus continues my ongoing investigations into colouring clay and ceramic bodies with stuff around the house. Step 1 in making Copper Carbonate involves making copper acetate (affectionately known as [Cu(OAc)2] to some, not me) because you need this stuff to make the carbonate later. It's as easy as mixing vinegar with hydrogen peroxide in a 1:1 ratio, dropping a piece of copper into it, and waiting. Within minutes, the liquid begins to turn blue, bubbles form, and hydrogen gas drifts out (you could actually see it like a smoke, although it was too faint to photograph). No smoking or lighting matches when you do this because hydrogen is flammable - I don't know how much hydrogen was produced, but I wasn't about to exp...

Another simple way of affecting the surface of a clay body is with terra sigillata (latin for "sealed earth"). It's basically a very thin liquid slip, i.e. tiny particles of clay suspended in water through the use of a deflocculant. The deflocculant is an electrolyte that ends up changing the electrical charge on some of the clay particles so that they are not attracted to each other and therefore don't gather together in clumps or "flocks", and instead they float individually in the water. What you end up with is a liquid that you can paint on your greenware and then polish to get a shiny surface on your fired piece. For a lovely example, see this shiny Greek vase: Most terra sig recipes I found called for clay powder, water and a deflocculant like sodium silicate or "old-formula Calgon" (the kind with lots of phosphates) but since I had neither, I found some heavy-duty tile cleaner at the hardware store which is trisodium phosphate, and use...