Expert: Leisha Hiester - 6/13/2008

Question
I lucked into a ton of cornwall stone for free. i would like to use this to make a
cone six porcelain clay body. Also I would like a good glaze base that uses
cornwall stone can you help. Thanx

Answer
John,

Congratulations on your luck. Cornwall stone is a feldspar. It's used to give strength to clay during the firing and in engobes to create adhesiveness when paired with a suitable flux. It's used as a glaze and referred to as 'English Cornish Stone.'

First, feldspars are among the materials used by ceramists that you need to take proper safety cautions with. Be sure to well ventilate & don't clean with a vacuum. It's safer to mop. Always think safety wear a respirator or mask, disposable gloves, safety goggles, etc.

I highly recommend you pick up a book on mid-fire recipes. I've been firing Cone 6 versus high fire for the last year with great success. But, it came through trial & error & testing. Test, test, test. There are so many great recipe books out there now. Think of it like a cookbook. You have to match your taste. I could give you a recipe I like, but if your definition of 'hot' is spicy....well you get the picture. I picked up "Electric Kiln Ceramics" by Richard Zakin first & then a few other recipe books & went to town.  

Your location, your kiln, your available materials, etc. will effect your results. I switched out my kiln & had to make adjustments mid-year. You're headed for a great adventure. I never thought I would be selling wares that aren't gas fired. I'm loving it. Just yesterday I sold a 'test' piece. I've learned to make very small bowls that I test new glazes on. If they don't turn out just exactly how I'd hoped, they still sell. This way I also pay for my 'testing'.

I hope this helps. Let me know if I can be of further assistance. I'd love to hear back how your adventure turns out.

Leisha