Tuesday, September 8, 2015
In a previous post, I explained how I first make 200 gram (about 2 cups liquid) trials to test glaze formulas on 3" x 4" clay tiles. From those I chose six to try out in a large enough batch to see how they perform on pots. If these new glazes perform well, I'll make 3 to 5 gallon batches so that I can dip larger pots and won't have to replenish the supply as often.
A glaze that "performs well"
The glazes I make are called "dipping glazes" or "bucket glazes" because I dip the pots into the bucket of liquid glaze, or pour the glaze over parts of a pot to coat it. A good dipping glaze stays suspended, does not "hard pan" (settle into a very hard layer), coats the pot consistently, does not "drape" or make unsightly thick rivulets on the pots when they are pulled out of the liquid, and does not become too powdery to handle when dry. It often takes several trials to create a glaze that behaves well in the bucket, melts correctly, shrinks at a compatible rate with the clay, and looks great on the pots.
Space is limited in my garage-studio, so I store the liquid glazes in food-grade lidded buckets on rolling carts that I can move out of the way when not in use. Small stainless latte pitchers with open handles are handy to hook over the rim of each bucket, ready for pouring glaze into the pots.
Initially I use a power drill with a paint-mixing paddle to stir the glazes, and then put a long handled spoon in each bucket to give the glaze another stir right before I dip or pour, in case some of the heavier ingredients have settled. Another essential is a bucket of water and a small sponge to wipe glaze off the foot immediately after dipping. After the glaze has dried I do a final sponge cleaning with fresh water before each piece goes into the kiln.