Tests are important, that sentiment has certainly reared its adamant head in this blog before (though it is mainly as a reminder for myself). If you recall in last Tuesday’s “Techno-ology” post I talked about Mason Stains, and them discontinuing a line of colorants. I wanted to do a new test run of colorants, as I use stains in my poke-a-dots (see cups below at leather hard stage) and am in search of some new colors. I rang up Greenbarn Ceramic Supply to order a “test kit” and bah! they no longer do test kits. But, you can get a little container of stain for $2. So I ordered it up (see photo above) and began testing away.
No one can’t go testing all willy nilly like though. One ought to have a standardized system so that all test results can be read easily and accurately. That is why I sat myself down and considered what information I wanted out of these tests. Below are some sketches of various test tiles I’ve done in the past. The two in the middle are best to see how a glaze will work on a vertical surface and the others for flat visual information. Regardless of what shape of test I end up with it is imperative that all the information I need to understand in three years time can be read on the back or front of the physical test, not in some random computer document or scrap of paper. This is information can be put on prior to firing with iron oxide or after with a permanent marker (that is the easier way, though it does ware with time. Ever written on a glassy surface with sharpie then subjected it to some abrasion? Well, you don’t have to, the sharpie loses.) The sketch to the right is a scan from my sketchbook when I was figuring out how to label and get the best information from my tests for colored slips. With this test format I end up with three slip colorant variations one stain at 1%, 5% and 10% with two glazes on top individually, a double dip of each and a sample of glaze A over glaze B and a sample of glaze B over glaze A. I even have a diagram on my studio wall to keep things clear (see photo above)! Next this week I am off to test various clear glaze. Also worth noting is that every glaze can change when the clay body is changed so it makes sence to test it on a few at the same time.