Having read the section by Kathleen Standen in the book Additions to Clay Bodies, I had an urge to make my own collection of stained clay test tiles - similar to the 'sweetie box' of tiles made by Kathleen.
The best clay to test colour is a white clay. I had a bag of grogged porcelain to hand and so began the process of weighing, mixing, adding, blending, shaping and marking.
I used 30 balls of 50g of porcelain. Each ball was flattened and the colour added.
Initially, I added the stain as a powder. This proved difficult to blend. As the clay was wedged between my fingers, it began to dry out and the dry stain was unable to spread through the white porcelain.
I next tried adding water to the powder...hmm, I think I can still see spots of stain on the walls where it splurged out of the clay ball!
Third time lucky...I added just enough water to make a paste. This was then squidged through the clay ball with much more success. In the words of Goldilocks it was 'just right'!
Below are the tests using various percentages of clay stain.
Above are the tests using percentages of oxides.
Upon asking Geoff which kiln they should go in, he suggested dividing each tile into three so that one third could be fired to Earthenware, one to Stoneware Oxidised and the final third to Stoneware Reduction.
I now have a collection of Trivial Pursuit pieces ready for bisque firing.
Update on test pieces after a bisque firing.
The tiles have faded during their bisque firing but will change again as they're heated to a higher temperature. (Top 10 tiles are Oxide)