frost resistant pots!

[nadesprockett]

Hi there, I've only worked with throwing, buff stoneware clays ...
I'm looking for a clay type or formulae that could be thrown on the wheel but used outside....that is resistant to cracking from frost?

Can anyone help with advice about what I could add in? or firing techniques that help with vitrification? Does that hinder the glaze or oxides that could be put on?

I'm looking for a clay that is still comfortable enough to throw with, but not a red/ brown teracotta base, so glazes and subtle oxides would still show well.....

I'd appreciate any advice, suggestions or experiences!
Thanks , all the best
Nadesprockett

[Andy Clift]

Hi Nadesprockett,
Stoneware is vitrified (non porous) so it is frost resistant, but if is filled with water and it freezes, the water will expand when it turns into ice therefore it will crack the pot.

Terracotta is not vitrified (porous) so a small amount can go into the pours of the ware and disengrate the pot.

So choose any stoneware clay for frost resitance, but know that water and frost can do damage to any clay body. Hope this helps your understanding a bit. I may be able to help you further if I know specifically what you are trying to do.

Regards,
Andy

[nadesprockett]

Thanks a lot for your post back-
that does clear up a lot for me indeed-
I suppose what I'm looking for is a clay that would show colour ( maybe wood fired, or light oxides, or even gentle impressions) - they would be lost I feel, on a red clay base.

I was hoping to put large plants in these pots , so I understand about the stoneware vitrificaton and that frost couldn't affect it......
But I suppose if you had wet soil ( or the potential to be wet often) that if there was an over night frost and below minus temps ( 'c) , would the water in the soil freeze and expand? and damage the pots?

I'm looking to do some elegant shapes that would be definitely outdoors.....the pots I would like to be large so the possibilty of moving indoors often might be very problematic........

as my only experience is with buff stoneware , I've also tried Krankkraft clay, very heavily grogged which looks like stone when fired.....but doesn't take colour so well.........
Would the heavily grogged clays have the same problems?

As many outdoor plants shed leaves or slow to near hibernation, I was thinking you could just maybe plant certain species and bring pots in doors for the winter.......but again its a lot of work and space needed etc.

this project is for a friends garden , as a wedding present so I'd like to get it right!

I've been looking up different plant pot makers and trying to see what clay they use etc..........

ok, thanks again for your quick reply and I'd really appreciate any suggestions or advice!
All the best
Sinead