If you just bought your kiln or if you’re using someone else’s, you want to be careful not to damage the kiln shelf. I’m sure you want to take good care of your investment. If it’s not your kiln, I’m sure you want to
respect someone else’s property. If glaze melts on the self, there is a slim chance your pottery will survive, and the kiln shelf now has melted glaze on it. No one wants to scrape, chisel, or grind glaze off the self or have to buy a new one. There are several ways to protect your shelf and your pottery from melting glaze.
What Is Kiln Wash
Kiln wash is a liquid resistant substance you brush on your kiln shelf that helps greatly in protecting your shelves. There are several different types of kiln wash you can choose from.
Basic Kiln Wash – A basic kiln wash is Kaolin and Flint
No-Crack Kiln Wash – No crack wash is Alumina Hydrate, Calcined Kaolin, and Kaolin
Salt Kiln Wash – A salt kiln wash is made up of Alumina Hydrate and EPK Kaolin
Applying Kiln Wash
How thick should the kiln wash be
When mixing the powder with water make sure it’s as thick as milk.
Is it better to brush or roll it on
Both are fine, just make sure you apply a thin coat. You can even spray it on. When applying kiln wash to your shelf make sure you apply thin even strokes.
How many coats should be applied
Two coats are the best. One coat in one direction and the second coat in the other direction. Some potters do one coat, and some do three. It’s best not to apply more than two layers because there is a greater chance of the wash flaking. If the kiln wash is applied too think it will flake, and the flakes will fly around inside kiln and stick to your pottery.
How long should you wait in between coats
Make sure the first layer is dry, a half an hour will do.
How Long Does Kiln Wash Last On The Kiln Shelf
Depending on how hot you fire the kiln and how often you fire will determine how often you need to reapply the kiln wash. When you drip glaze or see the kiln wash start to flake you need to reapply.
Reapplying Kiln Wash
Scrap off any glaze drippings and flaking kiln wash then reapply kiln wash by dabbing some on the bare spots.
When the kiln wash starts to chip and pit that’s when you should scrape it off with a putty knife and reapply.
If you have to grind, scrape, or chisel any glaze off make sure you are wearing protective eye goggles. If you are indoors and kicking up dust, make sure you are wearing a mask. The high amount of silica from the glaze can be harmful to your lungs.
Test Firing Your Glazes
Even if you clean the bottom of your pottery, the glaze may run down the sides and stick to your kiln shelf.
Test firing; After you have found your favorite glazes, it’s always wise to test fire them to see if they run. After you have fired the samples, label each one and keep them next to each glaze.
Labeling is good for two reasons. You know which ones run and you know what color they turn into after firing.
If you are using a pottery studio, the teacher will let you know which glazes tend to run more than others, and also have some samples of fired glazes.
Glaze Free Bottoms
When glazing your pottery, it’s important to make sure there is no glaze on the bottom of your pottery including at least a quarter inch up the rim.
Appling Glazes – There are different methods of applying glazes.
- Brush it on
- Spray it on
- Pour it on
- Sponge it on
- Dip it in the glaze
Any way you decide to apply your glaze is fine, just make sure you take a wet sponge and wipe the bottom clean. Be sure to rinse your sponge after every wipe. Otherwise, you will be wasting your time smearing the glaze around instead of wiping it off.
Waxing protects your pottery from the glaze. Any area you don’t want the glaze just put wax on. The wax makes it much easier to wipe the glaze off the bottom of your pottery. Like water off a duck’s back, one wipe and your bottoms are glaze free.
There are many different waxes you can try. These are just a few.
Wax Resist; Wax resist is easy to use, and there are many brands to choose from. All you have to do is brush it on or sponge it on the area where you don’t want the glaze. You can even use your fingers if that’s how you want to do it.
Stick Wax Resist; Wax resist sticks are just like crayons, in fact, you could also use crayons.
Paraffin Wax; Melt a paraffin wax bar in a pot. You can get the wax at any grocery store. Simply wax the bottom of your pottery to resist the glaze. It makes a nice even line on the bottom, and the wax burns off the pot when fired.
Beeswax; Gently melting three tablespoons of beeswax with one tablespoon of mineral oil makes a good resist and has a pleasant scent.
Candles; Candles may also be used. Gently melt your candle and brush it on the bottom of your piece.
Sampling is the best way to find your favorite wax that works best for you.
Cookies are clay slabs that are placed under your glazed pottery pieces to protect your kiln self.
However, they don’t protect your pottery. If glaze melts onto the cookie, your pottery will fuse to the cookie. If you’re lucky, you may be able to chip the cookie off your pottery.
How cookies are made; Cookies shouldn’t be too small or too large. If the glaze drips, the cookie has to be large enough to catch the glaze and not too big that it takes ups too much room in the kiln.
Cookies should be one-eighth of an inch think and bisque fired before using. Bisque firing takes the moisture out of the cookie. Keep in mind you can only use the cookie a few times.
A good way protect your pottery from sticking to your kiln shelf is to use stilts.
Stilts support your pottery while it’s being fired. There are several kinds of stilts made with a ceramic or metal product.
Stilts come in different shapes to support different sizes of pottery. There are Y shaped, round and triangular, they have vertical legs which are finely pointed. The sharp points leave almost no mark on your pottery.
Placing your pottery on stilts protects your pottery from sticking to your kiln shelf if the glaze melts and runs.
You can use shelf paper if you are low firing and if your kiln does not have a blower. The paper tends to burn, and the circulating air will blow ash onto your pottery.
- Keep a thin layer of wash on Your kiln shelf
- Don’t overglaze
- Keep the bottom of your pottery glaze free.
Taking these steps will save time, your kiln shelves, and your pottery. If you don’t take precautions, you will be wasting time trying to get the glaze off your shelf or spending money on new shelves.
POTTERY CRAFTERS THOUGHTS… With creating anything, there is always clean up and maintenance. There are so many different things you can do when creating pottery. From molding your clay to painting your pottery, each one is so much fun. It’s well worth the maintenance that’s involved.