Today I started my first glaze firing with the Geil kiln. Since it's controlled by a Fuji controller the firing is really simple (once the program has been set). It allows me to do reduction firing without having to make manual adjustments during the firing.
For those not familiar with pottery kiln firing, a "reduction" firing causes the air inside the kiln to be oxygen-deficient. That causes chemical reactions in the glaze that use oxygen from the glazes. Many glazes have a different look after a reduction firing than they would have if the air inside the kiln had the "normal" amount of oxygen.
The firing takes 13 hours - I started it at 5:45 AM so it will be complete a 7:15PM today. This is a "cone 10" firing - the temperature inside the kiln will reach 2330 degrees F. After the firing the kiln cannot be opened until it cools down. It won't be sufficiently cool until some time on Friday. I'll take more pictures and post results after that.
Glazed
Glaze can cover up problems. Here is the same pot after it was glaze fired.
This is the second bisque firing for my kiln. The firing was started on May 10 at 2PM and the fire was turned off at 5:27PM. The kiln door was opened on May 11 at 1PM.
All the pots made with the different clay bodies that I blogged about were in the kiln. The firing was successful (reached the expected temperature and nothing blew up) but there were various problems with some of the pots. I will update the previous blog entries to highlight the bisque firing results for those clay bodies.
This is the kiln after the firing. Notice the change in color of the pots.
"Soldate 60" is another clay body sold by Aardvark. Joe Soldate is a well-known ceramic artist from southern California. He developed a good clay body for clay sculptures. The original formula called for 30-mesh sand. Soldate-60 replaces that with 60-mesh (finer) sand. The clay is easy to throw. It holds its shape well.
The picture shows three tall vases with approximately the same shape. The one on the left was thrown using the clay I had brought from the Bay Area. The clay is re-worked left-overs. It is mostly "T2" with some "Sculpture Raku" and "Santa Barbara" mixed in. It's a little less than 12 inches high and about 8 inches wide at the widest part, 4.5 inches at the top.
The one in the center was thrown from "Bee Mix". This is 13 inches high, about 8 inches wide at the widest part and 4.5 inches at the top.
The one on the right is made with "Soldate 60". This is 14 inches high, 6.6 inches wide at the widest part and 4 inches at the top.
I'd be interested to know which shape you prefer. Please comment.
After Bisque Firing
The Soldate-60 tall vase did not survive the bisque firing well.
If you look closely you may be able to see the small vertical crack at the center of the top and a horizontal crack just above the fattest part of the pot on the right. Small cracks after bisque firing become large cracks after glaze firings so this pot must be thrown out
Another pot made with Soldate-60 (a bowl - not shown) survived the bisque firing. I'll show that after glazing.
"Coleman Porcelain" is another cone 10 clay body sold by Aardvark.
This clay fires to a clean white. It is very smooth - like butter.
I really like it for bowls and vases. I haven't tried to make a tall vase with it yet. I have heard that it can be difficult but I have not had any problems with it this far. Of course the pots have not yet been fired so a lot of things can go wrong before we see a finished product.
The pot shown above is a large bowl. (Note that there is a mirror behind the pot.) It hasn't been trimmed yet.
Here is a large vase still on spinning on the wheel.
Bisque Firing
Here are those pots after the bisque firing on May 10.
Glaze Firing
One of the pots was glazed using Celedon glaze - a lightly-colored transparent glaze. It was a reduction firing so the color of the fired glaze is blue. (It's green, normally.)
This entry will be updated after the other pot is glazed.
