Introduction
Ceramic test tiles are essential tools for potters and ceramic artists. They provide a way to test glazes, underglazes, oxides, and stains before applying them to final pieces. By experimenting with different test tile shapes, sizes, and firing techniques, artists can predict how materials will react under different conditions. In this guide, we’ll explore the various types of ceramic test tiles and walk you through how to make them, ensuring your glazing process is precise and effective.
What Are Ceramic Test Tiles?
Ceramic test tiles are small, flat, or dimensional pieces of clay used to test the outcome of glazes, stains, and firing methods. By applying glaze or other finishes to these tiles, ceramicists can evaluate factors like:
- Color
- Texture
- Opacity or transparency
- Glossiness
- Firing reaction
This is crucial for consistency and achieving desired results in pottery projects.
Why Use Test Tiles?
- Prevent Waste: Test tiles save time and resources by allowing you to experiment with glaze formulations and firing techniques without sacrificing larger pieces.
- Predict Results: The tiles give insight into how glazes and finishes will behave in specific firing atmospheres or temperature ranges.
- Documentation: Test tiles help artists keep track of glaze experiments for future use, building a library of reference materials.
Types of Ceramic Test Tiles
There are several types of test tiles, each suited to different testing needs. Here’s a breakdown of the most common types:
1. Flat Test Tiles
Flat tiles are the most basic and widely used for testing glazes. They are typically square or rectangular and have a smooth surface, making them ideal for testing uniformity in glaze application.
- Best for: Testing color consistency, surface texture, and overall coverage.
- How to make them: Roll out a slab of clay to about 1/4 inch thick. Cut into uniform squares or rectangles (around 2″ x 3″). Bisque fire them before applying glazes.
2. Dimensional or Sloped Test Tiles
Dimensional test tiles feature slopes or angles that help show how glazes behave on different surface contours. The variation in thickness allows for a more detailed view of how the glaze pools, breaks, or thins across a piece.
- Best for: Testing flow, pooling, and breaking of glazes on uneven surfaces.
- How to make them: Roll out a slab and cut triangular shapes or tiles with slight slopes. For extra dimension, you can press textures or curves into the tile. Fire and then apply glaze.
3. Textured Test Tiles
Textured tiles help ceramicists understand how glazes interact with different surface treatments like carving, stamping, or pressing. Glazes often behave differently on smooth versus textured surfaces.
- Best for: Testing how glazes highlight or obscure texture.
- How to make them: Use tools like stamps, carving tools, or other materials to create texture on your slab before cutting the tiles. Ensure a variety of textures on each tile for comprehensive testing.
4. Vertical Test Tiles (Standing Tiles)
These tiles are made to stand upright, providing a vertical surface that mimics the sides of a vessel or larger piece. They allow testing of how glazes behave with gravity—such as flowing, dripping, or pooling.
- Best for: Testing how glazes run on vertical surfaces.
- How to make them: Create a rectangular or trapezoidal slab and form it into an upright piece, often with a base that supports the tile. These can be bisque-fired before glazing.
5. Tile Racks or “T” Stands
Tile racks or “T” stands allow you to test multiple tiles simultaneously in a firing. They are particularly useful for batch testing and comparative studies.
- Best for: Testing multiple glazes at once, with tiles suspended vertically.
- How to make them: Create a base from slabs of clay and add vertical supports. This can be used to hold test tiles upright during the firing process.
How to Make Ceramic Test Tiles: Step-by-Step Guide
Materials You’ll Need
- Porcelain or stoneware clay
- Clay tools (ruler, knife, rolling pin, texture tools)
- Kiln for firing
- Glazes, underglazes, or stains
- Sponge and water for smoothing edges
- Bisque firing temperature (dependent on clay type)
Step 1: Roll Out the Clay Slab
Start by rolling out a smooth, even slab of clay, about 1/4 inch thick. For larger test tiles or those requiring more dimension, you can make the slab thicker.
Step 2: Cut into Desired Shapes
Use a ruler and knife to cut uniform tiles, which helps ensure consistency when comparing glaze results. The tiles can be squares, rectangles, or other shapes depending on the glaze testing needs (e.g., sloped, flat, or textured).
Step 3: Add Texture (Optional)
If you are making textured test tiles, press objects or carve into the tiles before drying. This will help you evaluate how different glazes respond to texture.
Step 4: Bisque Fire the Tiles
Allow your tiles to dry slowly to avoid cracking. Once they’re bone dry, bisque fire them in a kiln to make them sturdy enough for glaze testing.
Step 5: Glaze Application
After bisque firing, the test tiles are ready for glaze application. Be sure to label each tile with the glaze formula and firing schedule for accurate results.
Step 6: Final Firing
Fire the glazed tiles according to your firing schedule. After cooling, evaluate how each glaze performed on the different surfaces.
Final Thoughts on Test Tiles for Ceramics
Test tiles are invaluable tools for ceramicists. Whether you’re testing color consistency, glaze texture, or flow on vertical surfaces, there is a type of test tile suited for your needs. By investing time in creating different types of tiles, you’ll build a reliable foundation for understanding how your glazes will perform in a final firing, helping to avoid surprises and ensuring beautiful results.