Ceramic Test Tiles
I have a method for making test tiles for low-fire glazes. I start by making 3 inch squares from rolled out slabs. After smoothing out the edges and canvas marks, I paint a 1 inch strip of white underglaze on one end and a 1 inch strip of black underglaze on the other end.
Once bisque fired, I label the back of the tile with a black underglaze pencil. I write the brand of glaze, color name, and color code on each tile. Then I paint the entire tile with one brush-on layer of my.glaze. When that is dry, I paint a second layer of.glaze over two thirds of the tile, making sure to paint in a line that is perpendicular to my underglaze strips. Finally, I paint a third layer of glaze over half of the second layer.
This method generally creates nine distinct squares of color on the tile after final firing. I can see what a thin coat of glaze over a dark color looks like versus a light color or what a thicker coat looks like overall.
By testing the glazes over white, black, and the bare terra cotta I can make a pretty good guess what a glaze will look like over other shades of underglaze and how many coats I need to apply to get my desired effect.
Test tiles in various stages of completion
Close up view of the 9 square color tests