Category Archives: saggar

Thinking about kilns

I’ve been reading a few books on kiln building lately, trying to figure out something that will work at home without having a full-blown kiln yard in the backyard. Ideally portable, easy to set up, (fairly) easy to fire. Since I tend to make lowfire work, looking at smaller more primitive alternative kilns has given me a few ideas. Mixing that in with modern technology, materials, and know-how should lead me to come up with something. I’m leaning toward a ceramic fiber cylinder (or possibly cube), fired with a propane gas burner or two. Ideally, I’d like it to be able to do a low bisque, and be capable of tinfoil sagger, raku, or horsehair firings. It might end up being a single base with different interchangeable chambers, I don’t know. I’m just getting to the point of actually trying to run the numbers and calculations on heat output and retention.

Coincidentally, I ran across this video of an archeological team that found an old kiln site in France and decided to try firing it. The audio is in French, but it’s just interesting to watch and follow along as they rebuild the walls and fire it.
The Google translated link so you can read the text is here.

Enjoy!

Getting back on track

It’s been a week tomorrow since the big wreck, and I’ve been at a bit of a loss as to what to post. It’s pretty clear that I won’t be back in the studio any time soon. One of the more painful injuries is a very bruised, very sore sternum. I don’t even like to think about trying to wedge or center clay.

I do have some pieces from my failed attempt to re-familiarize myself with the old #112 claybody that are coming through the bisque firings at the center, so I’ll be able to glaze them soon. I did take the remainder and wedged it up on the tables and sprayed it down. Hopefully it got a good dose of microbes to help it age. It should be good and ready by the time I’m ready for it again.

I never got a chance to say anything in all last weeks excitement, but I’d thrown in the towel, raised the white flag and went back to my old familiar white stoneware. I’d been trying and trying to get the 112 to work for me, and was just being frustrated. My clay time is precious to me, and I just decided I didn’t want to spend my fun time being frustrated and pissed. I threw a 12″ vase on the first try.

I’m also spending some time going through old notes I’ve collected, ideas, sketches, etc. (when I’m not sleeping… I’m doing a LOT of sleeping). Maybe I can get them more organized and possibly share some. And there’s been some interest in more details of the naked raku and aluminum foil saggar techniques, so I hope to post more stuff about all that too.

The blog has been up for a little over a month now and I’m having a lot of fun with it. I’m enjoying the community, and have made new acquaintances from around the world.

Saggar Firing – Lessons Learned

After going over the test results of the experimental pieces I did at the last saggar fire, I learned a few things. Some are probably obvious to those more experienced than I.

For any color at all besides black, some kind of metal salts/oxides are required. I probably should have realized this, but I was hoping perhaps some of the trace minerals in certain organics would be strong enough on their own, trapped under the aluminum foil. They weren’t. Their main function seems to be to influence the colors/shades of any major metals already present. Ferric chloride, copper carbonate, and copper sulfate are all good starting points.

Pieces of broken off pinecones give a nice dark black. If you want good blacks, pinecones and needles are a good bet. It also doesn’t take much, start conservative.

Brushing on ferric chloride works just as well as spraying. And it’s a LOT safer, in my opinion. Airborne ferric chloride is just bad news. You still want to wear plastic gloves and be very careful. It’ll also ruin your brush, so use a cheap one, foam works well. I want to experiment with building up varied layers of diluted FeCl in the future.

Wrapping potsTinfoil saggars are the way to go, in my opinion. Comparing with other work from clay saggars, and pit firings where some was wrapped in foil the same way and some not, the colors just seem to come out more intense. You can also achieve good results with much less raw material since you don’t have to fill the space between the saggar and the pot. That’s just my personal taste. Some people like more delicate, muted coloration and that’s cool too. And despite reading in several places warning about not firing past the melting point of aluminum (1100F), I’ve never seen or heard of a problem with it. The aluminum foil doesn’t melt, it simply burns away. I think the regular weight stuff works fine, but experiment with some heavy duty and see what you like.

Terra Sig takes the color just as well as burnished or unburnished clay. I thought that maybe since it is a tightly packed surface of smaller platelets it would be less permeable to the smoke and fumes, but it didn’t seem to be a problem. Your clay, however can make a big difference. Earthenware bisqued to cone 06 is much less permeable than a mid/high fire stoneware bisqued to cone 06. The colors are still very nice, but are lighter and more delicate. Again, lots of room to experiment.

More detailed instruction is available in Alternative Kilns and Firing Techniques by Watkins and Wandless. It’s chock full of ideas, many of which can be mixed and matched between the different techniques. This one will really get your imagination flowing.

For more posts about saggar firing, click on the SAGGAR tag below.

Light red/pink swirl vase

Here’s one of the experiments that turned out.


When it was bone dry greenware, I first put a layer of white terra sig on it, then a couple layers of red. I originally intended for it to be much more red, and more of a solid coat, but the clay had other plans. Turns out the red sig streaked as the pot spun on the wheel, I’m guessing because it was still too thin/watery. I think it’s far nicer than what I was going for.

Natural finish

Here’s two views of one that wasn’t burnished or terra sig’ed. It has a natural raw clay surface.

It’s possible to seal it with an acrylic resin type product, but I think I prefer the softer colors. But it could bring out the lavendar/purples a little more…
What do you think?

Results

Overall, the results were very good. There were five of us total, and everyone was happy with their pots. It was cool seeing everyone else’s forms. Some small, some large, some handbuilt from textured slabs wrapped into vases.

Unlike glazeware, after the firing the work has only started. We had to unwrap and the scour the pots to remove the ash and residue from firing. Today I began the process of waxing the burnished / terra sig’ed ones. Kinda like waxing my Dad’s van as a kid, only smaller.

Here is today’s effort, after mowing the yard in between raindrops and other weekend chores.