Cone 10 Porcelain To Cone 6?

[Stone Spiral]

I have a friend who has a box full of bisqued cone 10 porcelain which she would like me to glaze and fire for her.

I am 100% certain it is cone 10 porcelain, as I was able to connect with the retired potter who created it - so I have it straight from the horse's mouth. I did my due diligence to make sure I knew exactly what it was - and was unwilling to fire it if there was any question.

 

So, historically, I have not done much cone 10 firing. In my studio I only use cone 5/6 clays and glazes.

I am trying to figure out what pitfalls may occur if I fire cone 10 porcelain to cone 6. I realize the clay will be underfired/immature, but I guess I don't know what that means - apart from fragility?

 

What else might I run into? Or is this perfectly fine?

I can throw one pot into my next glaze fire and find out, and I'm curious what I might be able to do to have this turn out.

OR - should I save my time and send the box back to my friend?

Thanks!

[neilestrick]

I think it depends on the porcelain. It might be tight enough to be functional at cone 6. If it's at 0.5% or less absorption at cone 10 it may well be under 3% at cone 6. You may get some crazing that you wouldn't with a cone 6 porcelain, and it won't be as glassy. If your friend really cares about the pots then they should be done at cone 10. Why does she want you to glaze them?

[Stone Spiral]

She wants me to glaze them because she'd like to use them (some as dinnerware, some as decoration). Right now, they are just bisqued porcelain sitting in a box. She rescued them when her retiring potter friend packed up to move away and was turfing all unfinished pots in their studio. So I e-mailed her now-moved-away retired potter friend to confirm clay body and cone temp.

[neilestrick]

I'd run a test to see if they'll be tight enough to be functional before glazing all of the them.