Pink to Blue? Who Knew!

Using local materials to create a stunning blue glaze

As you probably know, I’m fascinated by clay and rocks, particularly by what I can create with them. While it’s relatively easy to buy generic pre-ground and pre-mixed materials, I inherited a love of gathering and using local materials from my mentor, Michael Cardew, whose book, “Pioneer Pottery” is one of the foundational tomes of the studio pottery movement.

In light of this, I recently went on a rock gathering quest to get more of a pink granite out of which I make a glaze that turns a very pretty blue.

It took some sleuthing and hard work on my part, and my trusty 1993 Toyota van, “Hercules,” to get it back to the pottery.

After gathering this particular granite, I fire it in my gas kiln to 1800°F to “calcine” the rock. This causes the bonds between the different crystals within the rock to rupture, making it easy to tamp the rock into sand size particles.

These I put with equal parts of water into my ball mill – a rotating drum containing dense ceramic balls that act as a grinding media.

After eight hours of grinding, the rock is reduced to a very fine powder, and I empty the slurry, let the dust settle out, syphon off the water, dry the powder, and mix it into a glaze with a little limestone, which makes it melt at the correct temperature, 2375F, during the subsequent glaze firing.

The result is a fabulous, luminous blue glaze.
Pretty clever, eh?

Pink to blue? Who knew!