Back to the Smoke Firing
After the reaction to the smoke fired pieces, I feel more determined to solve the production problems that I have been having with these. Whereas the smoke fired pieces used to have a lot of colour and subtlety, they became increasingly monochrome and latterly just "spotted" with carbon. I have been randomly casting around for solutions and gradually realised I would have to be scientific to solve the mystery.
So I have been designing experiments to try and find my way back. This has been harder than I would have thought. There are so many variables. For a start, there is the temperature the pieces are bisque fired at (in the kiln). Then there is the clay (luckily only two initial variables here). I had originally used smooth clay. I changed this to the same clay, but with 20% grog added. Then there are the finishes (again, three variables - burnished, roughly burnished plus an application of terra sigilatta (for shine) or no burnishing and terra sigilata. I suppose the last variables are the smoke firing conditions (bin or pit, sawdust, dampness etc).
The mission is to work through each of these variables taking careful notes of the outcomes. The first experiment took place this weekend. I fired pot number 1 (grogged clay) and pot number 2 (smooth clay) to 980 C, both burnished with TS and then smoke fired these together with the same organic material (skrim). The picture is of the two pots in the dustbin ready to be covered in more sawdust and lit. The grogged pot did indeed resist the skrim "shadowing" and just "spotted" carbon. The smooth pot absorbed the shadow but remains black and white. I guess the conclusion is that grog is bad if you want patterns (not spotting). Having said that, I like the spotted vessel!
The second experiment should be done tomorrow. Pots 3 and 4 have been fired to 990 C this time - otherwise everything is the same. I am realising that this could take a while... but the prize is knowledge. At the end, I am going to understand better how to get the outcomes I am looking for.
Its time to do some proper homework.