Last month the 8th graders experimented with different earth oxides during their Chemistry block. They observed the effects of different combinations under extreme heat in a kiln to produce various glazes.
Here is an entry from one the the 8th graders journal:
When we visited Pewabic for our glazing class, we first learned and talked a little bit about glazes. The basic makeup of a glaze is made from chemical elements such as copper, brass and iron. We learned to mix our own glazes, being very precise with our measurements and wearing face masks to keep the dust out of our lungs. We experimented with different components and how they changed in the firing. We looked at our finished and fired tiles from the recipes we made. Some of the ingredients added were Rutile and Cobalt. After being fired, my tile was more textured, plain and white. We also discussed glaze flaws. Two such flaws are crazing and pitting. Crazing is when the glaze looks like it is cracked. Pitting is when a glaze traps gases that are being let off, which then leaves holes in the glaze. I really liked the way crazing affected some of the pieces, giving them more of a textured look. Through these classes, I found the endless possibilities of glazes very interesting.