search  current discussion  categories  glazes - chemistry 

thermal shock (ivor's posting)

updated sat 7 jan 06


Jon Singer on fri 6 jan 06

Ivor writes --

> Interesting to see some of the opinions expressed here.
> For a community that accepts, nay, promotes opening a kiln
> at plus 200 degrees C when the interior of the pottery may
> be well above that temperature the answers are intriguing.
> I am wondering if temperature scales are not linear but
> inversely exponential !
> Best regards,
> Ivor Lewis.
> Redhill,
> South Australia.

Hi, Ivor. Hi, all.

This is the wrong comparison.

When you open a hot kiln, you are exposing pots at
perhaps 225 Celsius to room-temperature air, which
is typically at 20-25 Celsius.

LN is at -196 Celsius and is a liquid, not a gas,
so a closer comparison would be to take a pot that's
at about 200 Celsius and pour icewater into it.

Even that isn't precisely equivalent, but at least
it's closer to being comparable; I suspect that you
will find that it does more than just craze the glaze.

Please note: anyone who actually cares to try this
should wear safety goggles and protective gear for
face and hands. Wear long sleeves, and long pants
or a full-length skirt. Be sure that none of your
clothing is meltable plastic (in other words, avoid
things like polyester). Better safe than sorry.

Best wishes --