My Pottery Journal

[George Lewter]

Since my last post I've written a lot about single firing and have purchased a PID controller to convert my manual kiln to programmable control.

7/17/09 Single firing means skipping the bisque fire and going ahead with glazing of leatherhard to bone dry greenware and then doing a full glaze firing. Read more on the "Single Fire" page under the "Technical" tab at the top of all our pages. I've also been mixing up some test batches of new glazes and applying some of my existing glazes in new combinations on test tiles.
My latest project is to try to convert my kiln to automatic operation with ramps and soaks programmable into the firing program. This type of control can add $500 or more to the cost of a kiln, but I expect to build and install the controller for under $200. I do have to say that the controller is daunting in its complexity of programming, but I believe the operation will be very straight forward. The difficulty is increased by the manual being written in English by Chinese people who are less than fluent in English. I do have electrical engineers at my regular job who can probably help me out with the tougher stuff. Here are pictures of the controller and the solid state relay that will rapidly cycle the kiln's elements on-off to achieve fine control of the heating and cooling.

Currently firing a load of glaze tests.

5/24/09 I'm doing a controlled slow cool-down to encourage crystalization and development of intense iron reds that I'm trying to obtain. I found a source for downloading the complete clayart glaze database. I'm extracting the mid-fire glazes and will have the document on our glaze page for you to download, hopefully in the next several days. It looks like there will be more than 200 pages of ^6 recipes and commentary.

More glaze testing tonight.

5/13/09 Working full-time just leaves me evenings to work on my ceramics. This evening I mixed up two glaze test batches. Tomato red was the first one. This is a retest because the first time I tried it, it came out a very ugly dull greenish brown, no matter how I cooled it. I've read quite a bit about what seems to be a common problem with getting ^6 iron reds to actually turn red. A number of people assert that the iron oxide is the key, so I'm on my third purchase of red iron oxide, though I find it hard to believe there can enough variation in iron oxide to affect its color development in a glaze melt. This one is the "special red iron oxide from Ceramic Supply in New Jersey. The second glaze is Richard Busch's Nutmeg. I tested it on a dark brown clay and it is a very rich tan breaking dark brown where thin. I'm retesting it on white stoneware prior to mixing a production batch. Richard Busch has a good article about using this glaze with a satin white, and a black stain for a woodfired look from the electric kiln. Will try to post pix after I fire.

Actually got a little work done this evening

5/12/09 I mixed batches and glazed test tiles for four ^6 commercial glazes from Crossroads Pottery Supply in Jackson Michigan. I'm looking for a combination of red and yellow, so I tried them individually on my dark brown body and my white stoneware body, as well as putting the red over the other colors. It's the first time in weeks that I've accomplished anything in the studio. I really have been in a funk over my lack of confidence in the glazes I have on hand. Hopefully, the rest of this week, I will be able to make test batches of another 10 glazes and some combinations of them and be ready for a glaze firing next week.

Help! I'm spending way more time on this network than I am doing pottery.

5/1/09 It's sad but true. I've had some ideas for things I want to work on in the studio, but spend much more time here in front of the computer than down in the shop. Maybe if I use this blog as a place to express my ideas about the work I want to do, it will get me "fired up" to get started.

My newest idea for some clay pieces is to explore the dynamic tension between religion and science. I'm constantly amazed by the battles between the two ways of looking at the world. For instance, geologists put the age of the earth at 4.5 billion years and Jewish scholars put it at a little over 5 thousand years.

To express on clay these opposing ideas I want to use writing. John Bauer appears to write on his pieces by sgraffito (scratching into the surface) and then leaving coloring oxides in the depressions and washing away the oxides on the high relief. I don't want to write long passages, and think short ideas will have more impact if they have the appearance of type. Deon de Lange (the creator of the intoceramics network at ning) appears to use type on some of his tile pieces, but I don't know how he does it. It may be fire-on decals for the small type and hand carved outlines for the large numbers.

My other great stumbling block is glaze inadequacy. My clear glaze is 100% reliable at running off the vertical sides of anything larger than a cup. I have several recipes to try for clear base glazes as well as other glazes and glaze combos. Glaze research is just not that exciting, but it must be done. I have two kiln loads of bisque ware just waiting to be coated with my miraculous superglaze. The only problem is that it doesn't exist yet.

[George Lewter]

Thanks for the thought, Graham. Actually my new clear glaze seems to be working great. It was on the two slipwork vases I just posted. It melts completely and stays put!