What Are Test Tiles?

The word “test tile” can refer to any shape of clay that’s used to test glazes, slips, underglazes, engobes etc.

Test tiles can be any shape you wish and can be made in a variety of ways. In this post, I’ll share lots of different examples of ways you can make your own test tiles. Here are examples of the test tiles I use regularly.

Extruded test tiles

Extruded test tiles

Wheel thrown test tiles

It doesn’t matter how you make them. The key is that they’re fast to make, they don’t use much clay and you have so many of them that you’re not afraid to grab them and test.

This way, you can do lots of experimenting and you don’t care what happens to them in the kiln. They’re not precious like your pots that you’ve put a lot of time and thought into. It’s always better to sacrifice a few test tiles than risk ruining your pots.

Use them often, whenever curiosity strikes. Try a new glaze recipe or a new combination of existing glazes. The more you test and experiment, the more glaze options you’ll have access to.

 

Styles of test tiles

Test tiles can be made in many different ways. To illustrate the variety of possibilities, I reached out to my Facebook group Understanding Glazes with Sue to see how other people make their test tiles and I have a lot of great photos to share with you. I hope these examples give you new ideas of ways you can make test tiles to test glazes.

 

Shapes cut out of a slab that sit flat in the kiln

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1. Textured wall tiles from the studio where I work – Cedar Hill Rec Centre in Victoria, BC

2. Raku test ornaments by Bonnie Martin McCormick

3. Flat, stamped tiles that will be hung on pegboard hooks by Debbie Peeples Diz

4. Flat, stamped, slip decorated tiles by Jacquie Blondin

 

Shapes cut out of a slab and propped upright in the kiln

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5. Nicholas Feisst stands his flat tiles in holders made from old clay scraps.

6. Don Clark stands his flat tiles in cut fire brick, inspired by Ron Roy.

7. An extruded test tile firing rack, similar to a Scrabble tile rack. Flat tiles lean can upright against the back of the rack.

 

Extruded ‘L’ shapes

       

These are the extruded test tiles that we make at my work. That’s the extruder die in the centre.

 

Extruded tubes

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8. Clay is extruded through a tube shape and then cut into smaller sections – Jacquie Blondin

9. Extruded tube with a different test on each side – Jacquie Blondin

10. Dipped extruded tubes by Rachel Gayfield

 

A ring thrown on the wheel and cut into sections

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11. Clay rings thrown on the wheel and then cut into sections – Eleanor Hendriks

12. Texture lines are easily added during the throwing process – Eleanor Hendriks

13. My wheel thrown test tiles were made inside out. I stamped and put holes in them after cutting them out.

Throwing test tiles on the wheel is a great way to make upright tiles when you don’t have an extruder.

 

Pinch pots

I make tiny pinch pots for when i need a bit more info than a tile can offer.

 

Other small test pots

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14. Small test bowls are made by pressing a slab into a disposable small sauce bowl – Brenda Keirsebilck

15. Callie Beller makes these testers that fit nicely in between large bowls in the kiln. The cone shape slows down glaze runs. They can be strung together to keep them organized.

16. Griet Vandenbussche first tests with small tiles and then the ones she wants to test further are tested in these small bowls she throws off the hump.

 

Different tiles for different purposes

Each style of test tile will provide different types of information. I recommend making test tiles that resemble your pots in some aspect.

If your work is 3 dimensional, it’s important that your test tiles have enough of a vertical surface so you can see how the glaze moves. A glaze that’s fired flat can look very different than the same glaze fired on a vertical surface, with the forces of gravity at play. And you can’t see if a glaze is going to run if you fire it flat.

If your pots are highly textured, make textured test tiles. Smooth pots, smooth test tiles.

Ashley Keller hand carves her test tiles. This shows her whether the glaze will accentuate her designs.

If you work in several clay bodies, it’s good to make test tiles out of all of them. Glazes can look and behave vastly different on different clay bodies. Just make sure to indicate the clay body on the test tile somehow.

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17. Different types of test tiles, different clay bodies – Brenda Kiersebilck

18. Different types of test tiles, different clay bodies –  glaze testing workshop in Whitehorse, YK 

The clay bodies I use are numbered and I stamp the number into the test tiles. It’s good to mark them in some way so you can tell what clay body they are years down the road, if necessary.

   

If you use coloured slips or underglazes on your pots, paint some of your test tiles too. If you’re trying to find a transparent glaze to put over images and decals, put images on your test tiles.

    

Brenda Keirsebilck paints slips and engobes onto her test tiles so she can see the transparency of different thicknesses of glaze. This will often produce an unexpected colour where the glaze and engobe overlap.

You get the idea! Make sure the test tile will give you the information you want from the glaze.

If you think you’ll eventually want to hang them or string them together, make sure you put a hole in them so you have the option.

Adelaide Barbey hangs her test tiles on the garage door. She has examples of each glaze on 4 different clay bodies.

If you really want to learn more about glazes, developing the habit of testing is going to get you there the fastest.

I recommend putting at least one test into every glaze firing, whenever you can. Especially if you’re firing a glaze kiln once/month or less.

When those glaze firings don’t come around very often, take advantage of them. Make use of the empty spaces in your kiln to learn about your glazes and find new ones.

Do you have a different way of making your test tiles? Please share in the comments or come over to my Facebook group and add to our test tile photo thread. I love seeing all the different ideas people have to test their glazes.

If this post helped or inspired you, please share it with others.

 

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If you love learning about and discussing glazes, I'd like to invite you to my free social learning Facebook group called Understanding Glazes with Sue. The group is full of videos and discussions about firing, mixing glazes and fixing various glaze issues. Please join!

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