Advice On Firing My L&l E23T To Cone 10?

[terraforma]

I have a new-ish L&L E23T kiln with 3" brick; one of the reasons I chose it was its ability to fire to cone 10. Now it seems that I might want to actually start to do that once in a while—I will mostly use it for bisque and cone 5/6.

 

The motivation to do this is that since I left my last membership studio, I had a small load of cone 10 work gas fired at a friends studio, where I can also use her glazes. Despite the very reasonable $.05 per cu. inch cost, this load cost me $72—more than what two full kiln loads would cost in my electric kiln, and almost double what the friend said it cost in gas for one firing in her kiln! Obviously, that is not sustainable.

 

I know I can't achieve the things I could with cone 10 reduction, but I will limit the firings to what will be happy in oxidation—matte and gloss white, matte black, crawl glaze, and Heino and/or Laguna turquoise.

 

Any advice or words of wisdom about cone 10 electric firing? I'm very new to doing my own firing. I've included a pic of the spectacular Heino glaze from that last gas firing mentioned above; if I could anything close to this in electric oxidation I'd be a very happy potter!

[Marcia Selsor]

 

First, ^10 is very hard on the elements of an electric kiln. They will last much longer firing to ^6. In 1980 while I was teaching, I switched from ^10 reduction to ^6 reduction to reduce time and energy consumption firing the kilns. I was firing 4 gas loads per week. After retiring I was using electric kilns and spent a long time testing many glazes and with help from other potters, I started getting results I likes.You can achieve very good glazes including iron reds if you fire down and hold the temperature for 20 minutes to an hour.

 

 Marcia

[glazenerd]

Several tips:

 

1. Reformulate glazes so that you can fire to high 8 to low 9. (and still mature the clay)

2. Fire to cone 9 with an extended hold to produce ^10 results.

3. Rope the lid if a top loader: cone 10 creates alot of static pressure that will slightly raise the lid. I have a 40lb block I use as well.

4. The last 100-150F uses the most power, and is the hardest on elements. Slow the ramp down for this last segment so the power demand is lowered. I have programmed a 120F an hour for the last ramp to peak.

 

Nerd

[neilestrick]

There is very little reason to fire to cone 10. Firing to 10 in the electric kiln will not usually produce the same results as the gas kiln, and if they do look the same then you're better off reformulating the glazes for cone 6 and saving your kiln. The main reason cone 10 pots look the way they do is because of the reduction, not the temperature. And many cone 10 glazes do not respond much to the reduction either. Cone 10 glazes can be brought down to cone 6 fairly easily. If you're using white clay, you won't be able to tell the difference between reduction and oxidation, and there are speckled brown clays for cone 6 that look like reduced stoneware. Save your kiln, save energy, save the planet and fire to cone 6. The Heino glaze would not be difficult to bring down to cone 6.

[oldlady]

i have the same kiln you do and i did some cone 10 firings years ago.  not worth it.  the effect i was looking for was caused by reduction, not temperature.  had to replace the elements sooner than i thought i would, too.  

 

cone 6 glazes can be beautiful and the use of rutile and titanium gives a wonderful effect.  look for glaze recipes containing them and try some out at cone 6.

[terraforma]

First chance I've had to check back on this discussion. Thank you VERY much to all so far who have answered. And to neilestrick especially—truly a revelation I have to study further, that I can reformulate the Heino Turquoise for cone 6. I will have to do much studying of glaze formulation to see what I can do about this. With its spectacular complexity of color and speckling, I miss this more than perhaps anything else about cone 10 reduction firing—second most-missed for me are the wonderful gradations of toastiness and speckling of the clays themselves.

[neilestrick]

There are lots of speckled cone 6 bodies that look really good.

[David Woodin]

First chance I've had to check back on this discussion. Thank you VERY much to all so far who have answered. And to neilestrick especially—truly a revelation I have to study further, that I can reformulate the Heino Turquoise for cone 6. I will have to do much studying of glaze formulation to see what I can do about this. With its spectacular complexity of color and speckling, I miss this more than perhaps anything else about cone 10 reduction firing—second most-missed for me are the wonderful gradations of toastiness and speckling of the clays themselves.

If you are still going to use cone 10 clay you will have to find out how low it can go wihout leaking,  You may have to switch to cone 6.

David