OWL POTTER on thu 22 jan 98
In my kitchen, are many pots by many potters, as well as my own, I love them
and use them every day in the oven and the microwave and I wash them in the
dishwasher.
The problem is: quite a few of these lovely pieces are growing a black mold
on their unglazed bottoms. The dishwasher does not completely remove this
mold. It is very unsightly, is it health threatening? I know this problem
does not exist in only my kitchen, because I have had customers in my booth
tell me they have had this problem, also.
Questions: How can I get rid of this mold permanently? (Through
experimenting, it can be gotten rid of temporarily with a liquid chlorine
bleach like Chlorox.) I have even re-fired some of these pieces; but, I am
afraid to re-fire other potters' pots. How can I prevent a reoccurance of
this mold?
Most Important Question: How can I be absolutely certain my future pots will
not be growing mold in my customers' kitchen cupboards?
I hope someone out there can help me. Thanks in advance for any help with
this.
Carolynn Palmer, Somerset Center, Michigan
amy parker on fri 23 jan 98
I have a flat-bottomed plate that I recently made that is the ONLY pot that
I have in my possession that has this problem. It seems to be more porous
than most of my "cooking" pots that go thru the dishwasher. I found that I
need to turn it over to let it dry before storing it. Actually, my dishwasher
seems to leave water in the bottoms of most cups, even though they are upside
down. The dry cycle doesn't run long enough or hot enough to really "dry"
the water up. Since you have this problem with ALL of your pots, I suspect
that they just aren't dry when you take them out & put them away, and that
you live in a damp climate.
At 07:35 AM 1/22/98 EST, you wrote:
>----------------------------Original message----------------------------
>In my kitchen, are many pots by many potters, as well as my own, I love them
>and use them every day in the oven and the microwave and I wash them in the
>dishwasher.
>
>The problem is: quite a few of these lovely pieces are growing a black mold
>on their unglazed bottoms. The dishwasher does not completely remove this
>mold. It is very unsightly, is it health threatening? I know this problem
>does not exist in only my kitchen, because I have had customers in my booth
>tell me they have had this problem, also.
>
>Questions: How can I get rid of this mold permanently? (Through
>experimenting, it can be gotten rid of temporarily with a liquid chlorine
>bleach like Chlorox.) I have even re-fired some of these pieces; but, I am
>afraid to re-fire other potters' pots. How can I prevent a reoccurance of
>this mold?
>
>Most Important Question: How can I be absolutely certain my future pots will
>not be growing mold in my customers' kitchen cupboards?
>
>I hope someone out there can help me. Thanks in advance for any help with
>this.
>
>Carolynn Palmer, Somerset Center, Michigan
>
>
George Mackie on fri 23 jan 98
One approach would be to seal the bottom of the pot with an organosilicate
sealer, as used to winterize garden pots so they dont absorb water and
freeze and crack. You can probably get it in garden shops. I do all my
earthenware with it. It gets around the problem of the pot overheating in
the microwave oven too. George
At 07:35 AM 1/22/98 EST, you wrote:
>The problem is: quite a few of these lovely pieces are growing a black mold
>on their unglazed bottoms. T
Potwork on fri 23 jan 98
In order to have mold you have to have moisture. I've been using my own "pots"
for 15 years and have never had a mold problem. I think you must have to be
VERY sure the piece is COMPLETELY dry before putting it away..... damp and
dark = mold.
Hope this helps
Potworker
Carlisle,PA
Linda Arbuckle on sat 24 jan 98
In response to Carolynn Palmer question about pottery with unglazed
bottoms growing mold...
Yes, it's nasty-looking. A body that isn't vitrified absorbs water and
the dampness can foster mold growth.
Use terra sigillata on the bottoms of your pots to help seal them and
this will prevent the black mold. Terra sig has been covered
extensively on the list, so I assume there's information on
CeramicsWeb about it.
Linda
--
Linda Arbuckle
Graduate Advisor, Assoc. Prof.
University of FL Department of Art
P.O. Box 115801
Gainesville, FL 32611-5801 (352) 392-0201 x 219
arbuck@ufl.edu
Jreke on sat 24 jan 98
I wonder if you live in a moist climate or have some bacteria in your water.
I have never had any mold grow on the unglazed pots in my house, nor has
anyone ever said anything to me about it before. The standard mold killer is
bleach or TSP for walls, etc. I think I'd use bleach on my pots if I was
trying to rid them of mold. You might have a ph imbalance in your water and
if you give them a vinegar rinse it might help. Jane Rekedal
JJHerb on sun 25 jan 98
Carolyn Palmer wondered about mold growing under the bottoms of several non-
industrial pots with unglazed bottoms. I suppose the mold is just ordinary
mildew kind of mold that found a dark, moist place to grow. The pots are
washed in a dishwasher where they can absorb some water into whatever porosity
exist in the body. Carloyn didn t say if these are earthenware or what. A
pot sitting of a foot ring on a shelf makes a little dark undisturbed chamber
that is great for growing mold if there is moisture available. If the pot
body is porous at all, the moisture that soaks in during washing is certainly
enough to encourage fungus growth.
What to do? Store your pots foot ring up until they dry. Store your pots on
a ventilated shelf or rack. Allowing the water to escape from the clay body
should make the growth of mildew less likely. You could also glaze the foot
rim and bottom with a low fire clear glaze but that involves several risks,
including the ware exploding from the water inside.
To prevent this problem in the pots you produce, use a body that vitrifies
more than the one you use now or glaze the bottom of the pot to cut down the
surface area that is exposed to water during washing. Either of these things
should cut down the moisture available for mold growth.
Joseph Herbert
JJHerb@aol.com
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