change bisque temp

At school we bisqued at cone 08 and glaze fired to cone 10. At home, I bisque to 04 and glaze at 5 to 6. I've seen to big difference between the bisques.

"Lindsay MacArthur" wrote

The difference in temp from 04 to 05 is only between 20 and 30 degrees cooler, depending on which size cone you use. As cones are indicators of heat work, and not strictly temperature, this can mean very little difference in time depending on your firing schedule.

There should be no risk to your ware in your changing from 04 to 05. It probably will make little difference in your glaze absorption, though. Absorption depends in part on the clay body you use, which you have not mentioned.

I work with a version of English porcelain, and bisque to ^04. I've noticed little difference when bisquing to ^05 or ^06. But porcelain is a rather "pure" clay body. Depending on the organic material in YOUR particular body, you may experience increased pinholing in the glaze, due to insufficient heat burning out the organic matter during the bisque, which would then try and burn out during the glaze firing.

Try it on a few test pieces and see.

Hope that helps, Wayne Seidl

if your clay is 04 then it would not be mature at 05 ,and if you glaze at 06 the result PROBABLY would not be as good, because one should really bisque at least 2 cones higher than glaze firing. what is wrong with your glaze???in what way is it not firing right,??? it could be something else.

Lindsay, I bisque my ^6 stoneware to ^06. Works for me and it takes a little less electricity. Not that it costs that much, I figured out one day that a ^6 glaze firing was about $1.75. So maybe save a quarter or so.. I recently heard that the rule is that there are no rules.. Tony

Lindsay, what temp do you glaze fire at? I high fire in a wood fired kiln. My bisque is around 012 and lower. A lower bisque will allow the ware absorb more water.

My teacher bisques even lower in his noborigama (climbing kiln.) The top part of the chambers reach red heat, but some of the lower areas are much cooler. All of his work is dusted and then sponged with a wet sponge.

Lee in Mashiko

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Always test. Just kidding, It wont have much noticeable effect changing 1 cone. Try 06 or 07. I fire at 08. Watch for pinholing though. Thicker glaze may result so watch drippy ones. E

I fire to cone 10 in a Geil Kiln. When I got my kiln I was bisquing to cone 07. I didn't think it could make a difference from 06. Well I started to get pitting in my glazes and could not figure out why. Someone at Laguna Clay told me that if I didn't bisq high enough that gases would escape from the clay body in the glaze firing, causing pitting. So I went to cone 06 and the problem of pitting left. Take it for what it is worth!