Tuesday, March 23, 2010

Pottery: Mixing glazes

Pottery making is so much more than sitting at a wheel throwing clay into shapes. The steps from raw, wet, malleable clay to finished functional bowls, vases or birdbaths are many. The work can be back-achingly hard, dirty and even dangerous. There is good reason that the occupation of potter has traditionally belonged to men. In the old days clay was dug from the ground and refined before use. Glazes were likewise procured from the earth and kilns were fired with cords and cords of wood over many days.

Thank goodness for modern advances!

But even with electric wheels, ready-made clay and digitally monitored kilns, the work is still hard and dirty and even dangerous.

Don't ask me why I do it. I often wonder myself.

Oh yeah. I'm addicted to clay.

Yesterday I spent the afternoon on one of the back-aching, dirty chores. Mixing glazes from raw chemicals.

It starts with a glaze recipe or formula. This is where I always lament that I didn't do better in high school chemistry class. Glazes formulas are calculated by gram weight. If I want to decrease or increase the amount of glaze I have to watch my numbers. Each raw chemical or element serves a very specific purpose in the glaze- opacifiers, fluxes, colorants, etc.- and each is present in very careful percentages for certain effects. It's a science. And I'm a kindergartener.

Elements in their raw, powdered state are a health hazard. I have to be careful when I store and use them.

Plastic containers with lids work best.

Nevertheless, safety equipment is a must when mixing glazes.

I have an ancient gram scale on which I weigh all my chemicals.

I weigh out each chemical according to the recipe....

This iron will color this glaze a nice brick red. Iron strongly influences colors in glazes from blue to green to brown to black.

I put all the chemicals together dry in a bucket...

...carefully stir them together without creating too much dust...

....and add them to warm water. I do this outside to avoid the hazardous dust it creates.

After mixing I strain the liquid glaze a couple times through a strainer. After a day of mixing and carrying buckets of water and glaze around, my back starts to complain. I've learned to not over-do it. Someday, maybe I'll have a studio assistant for this stuff. Yeah. Right.

After mixing half a dozen glazes and straining the others that had frozen and thawed over the winter, I'm ready to glaze a kiln load of pottery for the next phase of production.


  1. I just keep hoping you don't die of cancer. Or get Alzheimer's.

  2. This makes me appreciate my bowl so much more...if that can be possible.

    And I second what your daughter expressed up there.

  3. Cancer doesn't scare me. But Alzheimers...

  4. Yeah, YOU getting Alzheimers probably scares ME the most...



Note: Only a member of this blog may post a comment.