Ceramic Dictionary - by Susan Mussi: COLORS

COLORS - Testing in pottery.

Color testing: you should keep a file on all the colors you use, classifying them according to the temperature at which they are fired. File not only the name of the color but also where you buy it, the industrial names of the ingredients and the measurement of everything needed to make it, plus two samples of each color and a photo of the sample. To test colors use a small piece of dry clay or bisque of what is going to be decorated.

With a dark color, mark on the back either a code or what you are testing. A code is better as the pieces are very small and there is a lot to write. Before long, you will have hundreds of such pieces, so mark them well and keep the different methods in different boxes.

One can buy small kilns for testing colors, which makes the firing much quicker but the color is never exact. It is better to fire them in the big kiln when firing other pieces.
The easiest way to keep samples is to hang them up, for this each piece is made with a hole. There are two ways:

a) They can be threaded onto a metal bar that is hung up, which means you have to take the bar down and take off all the bits to find the one you want.
b) Put a wire through the hole and make a hook and then hang them up, which allows them to be lifted individually.

If you make the pieces in clay for the trials, make them with a hole. If not, drill a hole in each sample, put a piece of wire through the hole and at the end form a hook. Make two samples, one to hang up; the other sample I stick on top of the pot or jar in which the color is kept. Always fire and make a test of a new color. A color with the same name but not the same make might be different.

From left to right: Test pieces – front, Test pieces – back, Test pieces to hang up.

Read more about: On how to keep your colors, the last photo in: Tenmoku