Is firing at a higher temperature for bisque than for glaze really that unheard of?

It's the way I was taught and have been firing. I've been working out of my home studio for the past three years, and the ceramists and potters in this area are often downright rude about how I am "doing it wrong."

I like the work I make and people buy and use it. In that sense, I'm not doing it wrong.

It seems like there should be at least some school of thought that coincides with what I was taught. Where is it hiding?

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Test tiles are always a great idea. The most common change I've seen in cone 6 glazes refired to cone 06 is a reduction in their glossiness.

We all know some ceramicists are quite snobbish about the "wonderful" look of glazes fired to cone 10 where many of the coloring oxides partially evaporate, but that's just one look.

I'm fascinated by the incredible variation in how industry makes china or dinner ware. This first method at Coors uses once-fire where the glaze is applied to the greenware, then fired once at cone 2.

This second method at Lenox fires the bisque to cone 9, polishes the bisque, then heats the fired bisque, applies glaze and refires to cone 6.

A third method bisques slip-cast porcelain at cone 06, then applies enamel and refires the ware to cone 14.

Another method, I can't find the video for at the moment, vitrifies the unglazed china at cone 12 on slump-mold plate setters, also called chums, dusted with alumina. After polishing off excess alumina, the dry glaze is sprayed onto the electrically-charged plates and fired to cone 9. Decorations are then added and refired to cone 016.

This ceramic PhD discusses dealing with the problems of shrinkage, slump, and drag at very high cone firings.

There's so many different ways to get something done. In southern California I've found the most arrogant and snobbish ceramic artists often don't even know how to make their own glazes. When people don't know much about a subject they sometimes develop rigid and simplistic opinions about "the right way" to do something.

We used to have a book at our studio which showed the work of several ceramic artists whose work was the result of eight to fourteen firings at different kiln temperatures. They had incredible depth and complexity.

I had people tell me when I started working in clay that it was a huge mistake to refire pieces but I tried it with pieces I wasn't satisfied with and now I do it regularly.  If I can't make it right, it will go into the shard pile anyway. 

There are those glazes that do not take kindly to re-firing.  I have not been able to come up with a hard & fast rule about which ones do & don't.  I did a test with 32 different iron reds & there were several of those that pitted & some were dull & some that went clear as a result of the re-fire.  There were those that came out way better than before.  I would have to know what was in all 32 glazes in order to make sense out of the results, & since quite a few of them were commercial glazes, that would not be possible. If you don't like how a pot came out, you certainly don't have anything to lose by re-firing it.  Now, if you kind of like it, you may be disappointed by how it comes out on the re-fire.  So choose wisely!  I have had a few that I wish I had left alone after the first fire.  Also you have to remember that the more times you stress the clay, the greater chance you have of breaking it.  If there are imperfections, they are more likely to crack &/or break the more times that you fire them.  jhp

This artist uses multiple firings to good effect.

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