[Clayart] Clayart Digest, Vol 50, Issue 43

[Larry Miller]

Nice to hear this discussed.  I'm puzzled by the empire firebricks in my
patio that have made it through 40 years and out lasted the paver bricks I
used in the border.
I think the firebricks absorb a lot of water, I remember soaking them
before mortaring with clay on the chimney.
Larry "Art" Miller in northern michigan where its cold.

On Wed, Feb 5, 2020 at 7:24 AM Michael Wendt <mwendt at wendtpottery.com>
wrote:

> 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
>
>
>
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