[Clayart] Clayart Digest, Vol 50, Issue 43

[Michael Wendt]

Hi Snail,
I have a funny thought...
usually, freezing happens from one side inward as an object cools, 
proceeding at a pace controlled by how cold and windy it is..
How about adding a 2" thick block of Styrofoam to one side of the item you 
are testing?
Rubber bands could secure it.
This would result in the freezing progressing from a cold side to a 
protected side.
I agree that the cycle has to go from frozen to thawed and the back to 
frozen many times.
I don't know if it matters but it would match reality more closely,
Fun discussion
Michael Wendt



----- Original Message ----- 
From: "Snail Scott" <claywork at flying-snail.com>
To: "Clayart international pottery discussion forum" 
<clayart at lists.clayartworld.com>
Sent: Tuesday, February 04, 2020 7:31 AM
Subject: Re: [Clayart] Clayart Digest, Vol 50, Issue 43



> On Feb 2, 2020, at 11:04 AM, ronroy at ca.inter.net wrote:
> A freeze thaw test could be done every day to see what would work…



Yep, I do this; just have to stick to a daily routine: Pull out each evening 
to thaw; return it to the freezer every morning. Or vice-versa.

The sample should reflect actual intended use: thickness, glazed/not-glazed, 
etc.  Boil (or soak for a few days), then seal in a ziplock freezer bag. No 
benefit to wiping it off; just bag it up. Freeze and thaw daily for months.

Staying frozen for a long time is no different than being frozen briefly 
just once. Clay is stressed anew every time it re-freezes, and stress that 
does no visible damage after one cycle may still open up cracks that admit 
more water, then freeze and split further each time until serious damage 
accrues. Valid test results require a repeated cycle of freezing.

We are trying to simulate years and years of exposure, so as far as I am 
concerned, there is no such thing as too much testing.

-Snail