Friday, March 12, 2010
Clay projects are done!
Here are the clay (now stone ware) projects after the final firing in the kiln! They are now ready to come home.
You will notice that now the glaze looks all shiny and the colors are MUCH different than they were before.
A glaze firing is set at the temperature recommended for the type of glaze you are using. The glazes used in the elementary classroom are called 'low fire' glazes and are non-toxic. These were fired at a Cone 06, or at about 2,000* F. That level of heat is enough to melt the silica (sand) in the glaze and change it into glass. The glass surface (and rating on the glazes) makes these projects food safe, so, yes, you can let the family eat out of it!
Many students were willing to 'gamble' on the outcome of their glazing by painting each successive layer of glaze a different color. Glazes don't blend together in predictable ways like paint would, so you can never really be sure what will happen when you layer the colors like this. However, we ended up with some truly beautiful galaxies of color on many projects, so I think most of the students were really thrilled with the outcomes!
Here is a picture that demonstrates how the glaze changes color in the firing process. In the picture below, the lighter blue of the finished cup on the left is the same glaze as the light, light blue of the unfired plate on the right. That is a mild transformation, though. Our yellow-green glaze transforms from a rust color!