It’s a common sight in pottery studios: a wall of colourful test tiles! But even if you don’t use that many different types of clay or glaze, it’s still a good idea to make test tiles.
What are test tiles used for?
- They provide a clear overview of your glazes, engobes and underglazes, as it can be difficult to tell what a glaze looks like from just a name or number. Making a test tile for every glaze, engobe and underglaze allows you to keep track of them and have an example on hand at all times.
- They also help you to see how a glaze reacts to a type of clay and to the firing process, because every glaze and every clay is different. A glaze on one type of clay can look entirely different on another. So, if you are using a new clay or glaze, it is better to make some test tiles first.
- Test new glazes. If you’re creating glazes yourself, you can experiment with the recipe and proportions of the ingredients. To chart the results of all this testing, make a test tile each time. This gives you a clear overview of the effect of each change you made to the recipe.
Different types of test tiles
Every potter has their own preferences when it comes to test tiles because there are different ways to make them.
- Tiles that are punched or carved from a slab of clay that has been rolled out. Once they’re leather-hard, you can add a hole in case you ever want to hang them up.
- Standing plates are made by throwing a ring on the wheel with no bottom and pulling the clay up to create walls. Make sure to add a foot ring. Once the ring is dry, cut out the tiles and smooth the edges with a damp sponge.
- Hollow cylinders are made with a hand press.
Glazing test
- Carve a groove into the tiles to create texture and see how the glaze reacts on an edge.
- Dip your test tile three times: first, completely; second, two thirds of the surface; and third, one third. This allows you to see the effect of a thinner or thicker layer.
- The same goes for transparent glazes: don’t apply them to the whole tile, but only to half of it. This will show you what the clay or engobe/underglaze looks like with and without a transparent glaze.
Numbering and taking notes
Always write everything down! The last thing you want is to have a test tile that you really like but not remember what glaze you used.
- So, while they’re still leather-hard, don’t forget to number your test tiles with a needle or a stamp. Alternatively, use a ceramic pencil after they have been bisque fired.
- Keep a record of which clay you used for every test tile, what type of decoration you tried out, which glaze you used and how you fired it.
One more tip: make test tiles for every type of clay you use, with one bisque-fired tile and one twice-fired tile with no glaze. This will give you an overview of the colour of the different types of clay.
