I have been asked about the winter hardiness of my pots. As a new potter I am of course not sure. My pots are fired to cone 8 1/2 or so. (Cone 8 is down, cone 9 is bent over). I would think this is enough, but I'm unsure. Could I try and place a pot or two
in the freezer? I would first fill it with bonsai soil and water it allow it to drain well then freeze it. Am I being silly or is this a good test?

Help!

Jay

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Could I try and place a pot or two in the freezer? I would first fill it
with bonsai soil and water it allow it to drain well then freeze it.

I don't think that would be an accurate test. You want to see how the pot will
respond to alternate freezing and thawing and fluctuating moisture levels. If
you want a realistic test you will need to bury one or two pots in the ground
and leave some outside all winter in various locations. The weakest part may be
the glaze rather than the pot itself.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)

Jay,

High fired stoneware is generally safe in freezing weather.

Regards,
Roger Snipes Spokane, WA Zone 5, or maybe Zone 6.
Politics is the art of looking for trouble, finding it, misdiagnosing it,
and then misapplying the wrong remedies. Groucho Marx (1895-1977)

----- Original Message -----
From: "J. Gettinger"


I have been asked about the winter hardiness of my pots. As a new potter I
am of course not sure. My pots are fired to cone 8 1/2 or so. (Cone 8 is
down, cone 9 is bent over). I would think this is enough, but I'm unsure.
Could I try and place a pot or two in the freezer? I would first fill it
with bonsai soil and water it allow it to drain well then freeze it. Am I
being silly or is this a good test?

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+++++ Questions? Help? e-mail +++++

At 08:00 AM 9/18/03 -0400, J. Gettinger wrote:
I have been asked about the winter hardiness of my pots. As a new potter I
am of course not sure. My pots are fired to cone 8 1/2 or so. (Cone 8 is
down, cone 9 is bent over). I would think this is enough, but I'm unsure.
Could I try and place a pot or two in the freezer? I would first fill it
with bonsai soil and water it allow it to drain well then freeze it. Am I
being silly or is this a good test?

Jay

First, let me say that I know practically nothing about pottery. But I have
watched my pots over the course of twenty years. The level of the
temperature below freezing has little or nothing to do with pots breaking,
except that they are probably more susceptible to shock at very low
temperatures.

The real problem of breakage occurs right around freezing when the pots are
wet. When I lived in Ukiah CA, zone 8, I had almost no problems with pots
left outside all winter if they were properly fired so they absorbed little
or no water. Terracotta pots, which are not high fired, exfoliated after
just a few months of freezing and thawing. When I moved to Kelseyville,
which is still zone 8, but significantly colder in winter, I began having
all sorts of problems with the very same pots. Even rather expensive
Japanese pots began exfoliating by the end of winter. This didn't happen
after record freezes, but rather in the spring when we were likely to get
an evening rain followed very rapidly by a freeze.

My assumption is that even high fired pots will absorb a little moisture on
the surface or very shallowly into the clay, and that if a 'saturated'
surface is quickly followed by a rapid freezing, it can split off a surface
layer (exfoliate). I have many nice ruined pots sitting not five feet from
perfect pots which are protected from rain by a roof overhang.

Hope this helps

Brent in Northern California
Evergreen Gardenworks USDA Zone 8 Sunset Zone 14

http://www.EvergreenGardenworks.com

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Brent alston says:

Terracotta pots, which are not high
fired, exfoliated after
just a few months of freezing and thawing.


I had a large tray exfoliate its litte feet off over
time during a winter where we had what is called
"killer frost" in California.

I am also a potter and know that clay preparation is
as important as hardness. I tried to make a large
deep pot for a pine. It dried perfect with no cracks.
In the bisque firing the walls exfoliated. I think
because I sent the clay through the slab roller twice,
folding in the process.

I think you have to consider the stress points on your
construction. Of course thrown pots don't have the
same stresses as slab pots.

Kitsune Miko

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