In a way, glaze calculations and mixing are very much like cooking. Both fields require a good balance between art and science, experience and inspiration, and in both, the results are magical and very useful. You can buy the just-add-water commercial mixes to have a guaranteed result, or you can learn how to mix glazes from scratch and customize them to enhance your portfolio. The key to success in glaze mixing is similar to cooking: start with a simple recipe, assemble all the required tools and materials before you jump in, give yourself enough time to complete the job, keep accurate records of results every time, then repeat the recipe faithfully until you get used to it. After mixing many glazes, you will be able to predict how to fine-tune the recipe to your liking.
The idea of mixing glaze or gathering enough materials may be intimidating, but just like cooking, you can start small and easy, just to see if you like the hands-on approach.
Minimum Tools and Equipment (1)
Scale (triple-beam balance or digital scale) measuring to 0.1g
Small glaze sieve(s)(#50 to #100 mesh)
Notebook and waterproof pens
Spoons, scoops, and spatulas
Mixing containers with lids
Motorized hand mixer
Safety goggles, dust mask, plastic gloves
Tiles for Testing (2)
The best tiles to test glazes on are the standing, vertical type so you can see how glazes move. Try adding a stamp or fingertip indentations to see how glazes break in the grooves. Be sure to add a hole at the top if you wish to hang the tile.
Labeling Tiles (3)
Use an underglaze pencil to write a number or name on the bottom of the standing tile. If you know you’ll be testing some runny glazes, carve in the number, name, cone, and atmosphere.
Measuring Dry Chemicals
For the first time testing a glaze, mixing a 200-gram batch would be sufficient. Always wear a professionally fitted respirator or a tight fitting dust mask, safety goggles, and protective gloves to prevent direct contact with any toxic or caustic materials or airborne dusts. Keep the area ventilated and wet wipe off the mixing area and your tools after each mixing session. Do not sweep, it will spread the dust into the air.
Adding Water to the Mix
Once you’ve measured all the dry ingredients, slowly pour water into the mix while using a hand mixer to observe the consistency. Measure how much water you use and record it to have a repeatable result in the future. There’s no golden ratio between the dry ingredients and water: for example, you can make the glaze thinner for spraying or thicker for exact placement with a brush.
Applying Glaze to Tiles (4)
Since the characteristics of a glaze can change based on application thickness, it’s a good idea to apply two different thickness layers to the test tile. If you like applying glazes a certain way, such as by spraying, dipping, or pouring, the test tile should be tested that way as well.
Recording Results (5, 6)
This is the most important part of testing and it will ensure you have consistent results when you want to repeat the glaze. Write down everything you did. Set up a system to record your results and make copies of the form to use in the lab and after unloading the kiln. A sample record format is available as a downloadable PDF here.
Store dry chemicals in sealable containers. You can mix your favorite glaze in a large batch as a dry powder and store it for later usage. To save storage space, you can store small portions of test glazes in freezer-grade resealable bags and keep them together in a larger container.
When you have a several glazes that aren’t quite to your taste or have too much of one particular mix, you can start cross mixing them to see if they change and improve. Sometimes two or three glazes work together and make a beautiful new glaze. Alternately try layering a couple of glazes, applying a layer of underglaze or wash before applying a glaze, or brush a wash/glaze on top of the base glaze to jazz it up. There are many little adventures you can have without a spray gun or a big studio facility.
Yoko Sekino-Bové is an artist and teacher living in Washington, Pennsylvania. To see more of her work, visit yokosekinobove.com.