These are test tiles to show what different glaze combinations look like. The problem is that for every glaze you have, the amount of combinations grows exponentially. Wow, didn't think I'd spell that right but my spellchecker is giving the ok.
So if you have a total of three glazes, there are 9 possible combinations (if you include the same glaze for both layers as a combo). If you have 4, there's 16 combos, 5 and 25 combos and so on and so forth. Part of the reason for that is because you want to see how they combine when you apply one glaze on top of the other, as well as the other on top of the one glaze. That is a whole lotta test tiles to make and fire!!
I have a ton of glazes. Seriously, I buy glazes like a Sunday comic strip female buys shoes. There is not enough kiln space in the world to test all of the possible combinations I could test. So we're narrowing this down a bit and making one big tile to test several combos.
And before you tell me, yes, that one broke just before being glaze fired and I had to glue it together after the fact. But it still gives me the info I need.
What you're looking at is a test tile of 4 different glazes in every possible combination they could have with each other.
And here's what other information I've designed into the tiles. I use several clays because I make a lot of agateware. Each of my new glazes is tested with a white clay and a dark red clay. But I've never tested with my recycled clay which falls somewhere in the middle. So for my combo glaze tests, I use the recycled stuff! So now I have a test tile of each of these colors individually on recycled clay. See how they are labeled on the diagonal? And each tile as a divot cut out of the center so I can see how the glaze combination breaks. And while you can't see it very well, the lower left segment of each tile has a rubber stamp impression to see if a stamp would be visible under that combo.
Making these things -
Obviously I make a slab. Usually a pretty large one.
I press a wire shelving cube thingy (you know, those wire squares that you can attach to each other to make cube like shelves, really cheap and portable, common in college dorms) into the slab to make approximately 1 inch squares. Then I carve off the edges and see how many squares in each direction I have. If I have more columns than rows, I cut off a column to make it square.
Originally I was going to go for about 7x7 but I found that those broke really easily. That's how I ended up with so many 3x3 kickin around. The largest I've made that has survived as been 5x5 and that ended up splitting in the final glaze firing. Still gives me the info I need though so it's all good.
Let dry and fire. If it breaks, try to salvage at least a 3x3 section if you can. Very nice to have if you just want to check one or two glazes with each other.
So now you have your fired grids. How do you keep track of what goes where?