Glaze testing. Recipes for glazes are everywhere. Just goggle. Or buy a great book like John Britt's "The complete guide to High-Fired Glazes" and you find pretty pictures and the listing of materials that if combined and applied will lead to beautiful pots. And they often do. But, somewhere there is fine print which basically says: "Your results may vary..." There are multitudes of reasons for this. The materials differ from mine to mine or even different locations in the same mine. Your application isn't the same. You don't follow the exact same firing schedule. Etc. Etc. So you do tests. As I am in search of my "style" and body of "coherent work", I try to put glaze tests into the kiln when I fire.
Recently I had the opportunity to do back to back firings in my gas fired Soda Kiln and then in my friend, Rob Harvey's, wood fired Salt Kiln. So I made duplicate test tiles for each kiln. The clay used was a stoneware made by Highwater Clay of Ashville, NC called Orangestone. The results were interesting and are shown below.
Okay, so? Well, they are different from kiln to kiln. Surprise? No. They are different from Soda to Salt glazing. Surprise? No. They are different from gas to wood fired. Surprise? Again, no. The tests also failed to find a nice blue. Lots of green, but blue? No.
So was it worth doing? You bet. I got two glazes that are working in both kilns right out of the box, Emily's Purple and Gold Shino. Plus a couple more that may work with a little more... glaze testing.