Monday, October 20, 2008
Fresh Out of the Kiln
At this point in my life I want to know a lot about clay in a relatively short amount of time, which isn't always possible, but that doesn't keep me from trying. We just unloaded the kiln this evening. From my perspective, I am progressing and learning a lot and the evidence is shown in this glaze firing.
Here you see one of my shell bowls made from Windsor porcelain clay with a beautiful blue glaze. I really like the way this glaze pools at the bottom and I also like the shape of the bowl. Windsor porcelain is a joy to work with in hand building. The clay accepts the glaze nicely and is a good fit. However, the glaze ran a bit at the bottoms of these bowls and will need to be ground down some. I have a set of four of these bowls and one cracked being removed from the kiln shelf.
Here you see the same form shell bowl made with Black Mountain clay with a painted fish under glaze and a transparent over glaze. This is the first time I have used under glazes and I have many more ideas to try with these types of glazes. The transparent glaze over the top has reacted with the iron in the clay body to produce an overall gray or gray-green background color which was not what I was after. I wanted the black clay body to show through.
I am not sure it is possible to achieve an actual clear glaze over a black clay body in a reduction firing. I have one more transparent type of glaze to try that is supposed to be good over oxides, not sure it still won't react with the iron in the clay body to produce the gray tones again. We shall see in the next firing.
If you recall our last glaze firing didn't achieve Cone 9. Here are the cones from this firing. The cones pictured on the left were on the next to the bottom shelf of the kiln and are probably almost Cone 11. The cones on the right were on the top shelf of the kiln and are not quite to Cone 10. We have a discrepancy between the top and bottom of the kiln tempratures and consequently glaze maturation varies from the bottom of the kiln to the top.
In previous posts I talked about my experimentation with platters and plates, I've been striving to achieve a good form from a slumped or humped mold without having the plates or platters warp. For this firing I achieved some successes and failures in that regard. Here is a new square form with four undulations and no foot, this form seems stable and didn't warp at all. The transparent glaze was supposed to allow the blue under glaze to show through, which it did. The transparent glazes was also supposed to allow the black clay body to show through, but again has reacted with the clay body to produce more of a grey tone and has obscured the color of the clay body. I think the transparent glazes are going to take much more experimentation.
This round porcelain plate is made from Windsor porcelain with a blue and salmon under glaze and celadon glaze over the top. The plate was constructed with a slump mold. The plate did not warp and was placed on the kiln shelf with porcelain sand underneath. I wish I had put a border design around the outer edge of the plate. I also want to practice more with under glazes, but I like how the color blended ever so slightly and the celadon almost acts like a clear over the under glazes.
I had high hopes for this medium square platter since I took quite a bit of time formulating, measuring and painting the semi-circle under glaze design on the platter. Here again I used Windsor porcelain on a slump mold with a flat bottom and no foot. Although the platter didn't warp, it does have a large crack on one side. I'd like to try this platter and this design again as it is one of my favorites - a semi-circle design on a square platter.
Previous crosses I have made have warped due to hanging attachments I placed on their reverse. With these next two crosses I left off the hanging attachments and they didn't warp. I will probably be attaching a metal hanger with epoxy to the back of these two. Although I did impress in a nail recess on the upper back, I am not sure that will be sufficient to hang them safely from the wall without risking their falling.
Stay tuned to see more from this firing in my next post where you'll see an unusual pinched and sculpted bowl, yarn bowls, free form bowls, and other bowls with some unique glazes.