Firing A ^ 5 / 6 Clay To Only ^ 02

[graybeard]

Hope everyone had a good Thanksgiving

 

Well, I finely had the chance to fire the clay Neil recommended (STANDARD #630) at home. My kilns are old electrics that have been well used and I don't feel they would stand up to many ^5/6 firings before the elements gave up the ghost, so everything I do has been low fire (^04/05).

 

The problem is the clay Neil used in his classes, it's a ^5/6, it was like butter, way easer (nicer, softer, less dense, smoother) to work than the Standard 105 and 103 I have been using ( so this is really all his fault.)

 

Cutting to the chase: I bisque fired the clay to ^02, the hottest sitter cone I have and there doesn't seem to any problem at all. I glazed a couple pieces (lowfire glaze) and fired them and again, no problem that I can see.

 

The question: what am I missing here, is this something I can continue to do? Or will I come home to find out that my mugs and bowls have turned to muddy slime or dust.

 

I really do like that clay, THANKS Neil!

 

Graybeard

[Chris Campbell]

What you have is clay that is not vitrified, not closed up. You will find items will absorb water in unglazed areas. Not a great idea for functional wares ... for instance a mug might dangerously overheat in a microwave due to that water boiling up in the cllay. And, yes you could actually get smelly bottoms. I would also expect them to chip more easily as they would be softer.

 

For decorative items meant to be displayed indoors, no problem. Actually, some people fire Cone 6 clays that way for Raku as the openness of the body give all kinds of nice little crannies for glazes to do their magic in reduction.

[neilestrick]

As long as your glazes don't craze, it's no different than working with the low fire clay which also won't vitrify at that temp.

[Denice]

Chris your comment about smelly bottoms made me smile.  Denice

[Mark C.]

You could put new elements in the old kilns and start vitrifying your clay -it would be much stronger -less weeping issues and hold up better in use .

[glazenerd]

If budgets are tight and new elements are not on the list. Do very long extended holds at peak: it will jump heat work or cone or so. Still not vitrified, but a bit more sturdy.    Nerd