Why Test Tiles Matter: Unlocking the Full Potential of Your Ceramic Work

Blog by @cilla_ceramics

If you’ve spent any time working with glazes, you’ll know that the liquid colour seen in commercial jars or personally made glaze is rarely the same as what your piece looks like when it comes out of the kiln. This is why test tiles become a crucial part of the ceramic process. Whether you’re a studio potter, hobbyist, or ceramics teacher, creating glaze test tiles is one of the most valuable habits you can develop. 

Why Test Tiles Matter

1. Glaze Results Can Vary Dramatically
A glaze’s final appearance is influenced by a range of factors—firing temperature, clay body, thickness of application, placement in kiln, and interactions with materials from other glazes. Test tiles gives you a small, controlled sample allowing you to see how a glaze will look under your unique firing conditions. 

Test tiles help isolate and control variables: 

• Different thicknesses of glaze on the same tile.
• Glaze over texture surface vs. smooth.
• Glaze over different clay bodies or slips.
• Firing position in the kiln.

2. Save Time and Materials
Skipping the test tile stage often leads to disappointing (and sometimes costly) surprises on finished pottery. A test tile uses minimal glaze and clay but can prevent a lot of wasted time, energy, and materials on work that doesn’t turn out as expected. You don’t want to ruin a kiln shelf or worse!

3. Explore Consistency and Record Variations
Test tiles allow you to experiment safely. The results create a personal reference library of glaze behaviour specific to your studio. You can tailor the glaze thickness, overlap glaze layers, or try different application methods (brushing, dipping, spraying) and record the outcomes. Clay surface as well as the type of clay can affect glaze development. 

One of the most frustrating experiences in ceramics is trying to recreate a glaze effect you once loved—only to find the results are totally different the second time around. That’s where test tiles become not just helpful, but essential. A test tile offers a physical, fired sample of a glaze on your clay, under your firing conditions no matter what cone you fire to. It becomes a clear, objective record—much more trustworthy than notes or memory alone.  You can see exactly how thick the glaze was, how it pooled in textures, how much it will melt, and how it reacted at edges or over other glazes.

5. Great for Troubleshooting
If a glaze cracks, crawls, or pinholes on a test tile, you can identify issues before applying it to a whole batch of work. If you do not own a kiln and must rely on someone else’s firing schedule you can learn what the glaze looks like in different kiln.  Also, availability issues with certain materials means you may have to get creative with temporarily or permanently replacing/ substituting raw materials that are no longer available. This controlled approach makes it easier to isolate problems and find solutions without sacrificing a full kiln load. 

Tips for Effective Test Tiles

Use the same clay body as your finished work—glazes can react differently on different clays.

Mark your tiles with identifying codes, clay type, and glaze information. You always think you will remember….

Vary the glaze thickness across the tile using ridges, textures, or angled surfaces to observe different effects.

Make your test tiles big enough, if they are too small of a surface area the test glaze cant give you enough information. 6cm height is a good starting point.

Make the test tiles vertical and ensure there is a sturdy support and catch tray. Glazes will react differently on a horizontal surface vs vertical.

Fire with your regular work so the test results are accurate to your firing cycle. Fills those gaps in the kiln with test tiles.

A Simple but Powerful Practice

Making test tiles might seem like an extra step, but it’s one of the most effective tools a ceramicist can use and it is fun! It supports creative freedom, technical confidence, and consistency in your work. Over time, your glaze test library becomes an invaluable resource—like a visual cookbook for your ceramic’s studio.  Knowing you can get the same results twice when using a glaze combination builds your confidence and credibility as a ceramicist. Whether you’re refining a personal style or managing studio production, having well-documented glaze tests gives you greater control over your creative process.