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We often get the question, "What do you do with that leftover glaze you don’t want?"
Most potters, when they have a glaze they don’t like or that isn’t working for them anymore, pour all such glazes into a single bucket. These mixes are typically called “slop glazes.”
Test the slop after a while and see what glaze you’ve got. Often it is green or brown color. It may be a nice liner glaze or even a decorative glaze. Some people separate their light color glazes from their dark color glazes, or separate their food safe glazes from their non-food safe glazes.
But what if the glaze is contaminated, or you don’t have a use for slop glaze? If you are sure it has no toxic chemicals (AP non-toxic label on commercial glazes), you can dispose of it easily by pouring it down the sink (also OK for sewer or septic) or throwing it away with the trash.
Many glazes after all are just clays and fluxes. But if the glaze has toxic chemicals, or if you’re not sure if it does, the best thing to do is put it in a bowl of bisque and
fire it. This will lock in the toxins permanently. Then you can throw the piece in the trash.
If firing the toxic glazes isn't an option, call your local waste disposal company and tell them what chemicals are in your glaze, and they will tell you how best to dispose of it.
Do-It-Yourself, or DIY, projects are insanely popular all across the crafts world, and ceramics is no different. Here's how to make your own glaze!
Equipment and Materials
To mix your own glazes you need:
- A sieve.
- A mixer.
- A scale.
- Glaze recipes.
- A mask.
- Two buckets.
Find a Glaze Recipe
Typically one starts by finding a glaze recipe, from a book or a reputable website. Start with a glaze recipe which is formulated for your particular firing type and clay body (i.e. stoneware clay, fired in cone 6 oxidation). Recipes are usually expressed in numbers that always total 100. For example:
- Ingredient A: 10
- Ingredient B: 25
- Ingredient C: 15
- Ingredient D: 50
Determine the Amount of Glaze You Want to Make
Determine the amount a glaze you want to make and then add the appropriate ratios. For example, if you want to make 1000 grams of glaze, you would add:
- 10 / 100 * 1000g of Ingredient A
- 25 / 100 * 1000g of Ingredient B
- 15 / 100 * 1000g of Ingredient C
- 50 / 100 * 1000g of Ingredient D
It is wise to mix a test batch of 100-500g first, to make sure the glaze works as you want it to. Glaze chemicals are measured using a scale.
You don't have to throw away all your clay scraps, but recycling them doesn't need to be a chore either. Here are some ideas for the environmentally-conscious potter.
- Throw with two separate buckets - one for clean water, one empty one for wiping the clay from your hands into. So, if you're right-handed, dip your hands in the right bucket of water, throw, then when they are full of clay, wipe them on the edge of the clay bucket on the left. Every so often wipe the clay off the edges and down into the bucket to keep it from drying out.At the end of the day, wedge the clay back up and make your last piece. If it is too wet, squeeze it into a long cylindrical shape and put it on a table curved like an arch. This exposes more surface area and will dry it out faster. Or try it the next day. Depending on humidity and temperature levels may need more or less time. Check it and cover when it is the right wetness.
- Another thing to do with throwing scraps is pour the slurry into a kitchen colander lined with a sheet of newspaper. Excess water will filter out. Note: Clay processed from throwing slurry is very plastic and nice to work with!
- After you've been working with clay slabs and you have that pile of scraps, dip them in water and place them in a plastic bag. Wrap tight, leave a couple days, then wedge and use it.