Glazing - Chemistry, Alchemy, and Luck!

I don't love glazing.

Without a doubt, it's the hardest part of pottery.

Not only is there a ton of science/chemistry involved (which I love), but there's even MORE trial and error (accompanied by random luck -- which I don't love).

If you read a few books on Glazing, you'll repeatedly see the motto "Test, test, test!" Because even if you have a precise technical recipe for a glaze, all of the following will affect how the glaze comes out:

  • Kiln Environment
  • Kiln Temperature
  • Kiln Firing Cycle
  • Clay Body
  • Quality / source of ingredients
  • Thickness of application
  • Glaze on ADJACENT pieces in the kiln
  • (and many, many more factors)
 Coyote White Crawl Glaze, ^5-6

Coyote White Crawl Glaze, ^5-6

So, with that in mind, I've been hunting for a glaze! Specifically, a white crawl / lichen glaze. These glazes have such a high surface tension that they 'draw' up on themselves, creating a cracked surface that looks like a dried up river bed or salt flat.

This past weekend, I spent a few hours in the Glaze Room at my studio, and mixed up some new (and old) glazes. I'm so fortunate because The Potter's Studio in Berkeley has some amazing glazing facilities, including a brand new ventilation system to make sure I don't inhale any toxic dusts.

Here you can see me doing a time-lapse dance while whipping up a batch of my favorite Shino glaze-- measuring ingredients out, mixing them in water, sieving them (a few times), then measuring the right amount of water. 

After a long day, I ended up with three test tiles to try out! One for my favorite Shino (to make sure I mixed it correctly), and two different crawl tests. 

 Test Tiles: Shino (left), Crawl #1 (middle), Crawl #2 (right)
IMG_7572.JPG

Mixed results! My Shino turned out as expected (on the left), and the middle lichen glaze I'm pretty happy with. Some of it flaked off, but that's controllable with application.

The glaze on the right... Is why glazing is so hard. I followed the recipe to the letter. I applied it, and I could see it cracking as I expect crawl glazes to do. BUT, the final result hasn't crawled even a bit! It looks like a normal, brown-ish glaze.

 Pieces to glaze next week!

In the end though, I count this as a success!

I found a lichen glaze that works for my clay body / kiln, and am ready to start glazing some pieces in the upcoming weeks.

New pieces to glaze! ==>