David Hendley on sun 11 jan 98
Cynthia,
I don't think you should expect to be able to heat food in a
microwave on a large plate made with an ordinary stoneware body.
Think about it.
Say you plop a pile of mashed potatoes on one section of a plate,
so about 1/3 of the plate has food on it and 2/3 of it does not.
If you nuke it on high for a while the potatoes will get very hot.
The heat from the food will transfer to the plate, but this will be
concentrated on only one small area of the plate.
Uneven heating will cause the plate to crack, the same as if
you put the plate on a heat source.
This is not a problem with a mug or a bowl because, since they
contain liquid, the heat is evenly spread over the whole piece.
I've never had anyone complain, but, being a cautious guy,
I tell my customers that my plates can be used in the microwave
IF the food is evenly distributed over the plate and a LOW to
MEDIUM setting is used.
That said, I do agree that your plates broke entirely too easily,
and I hope your new clay does better.
But, now I'm wondering what others think about this.
Do you think a plate should be able to pass the "steaming mashed potatoes"
test?
Anyone?
At 06:21 PM 1/10/98 EST, you wrote:
>----------------------------Original message----------------------------
>Ron:
>Your message about firing clay too high made me wince. I threw 17 large
>dinner plates for a set for my daughter (the extra 5 so I could make
>them match.)
>She oo'ed and ah'ed when I gave them to her. Several months later she
>called to tell me that l plate broke when she heated some food in the
>microwave. How can that be?, I said. All of us potters are telling our
>customers our work is "microwave, oven and dishwasher safe". The next
>week another plate broke under the same circumstances. The next week
>all she did was put an ear of corn from the steamer onto a third plate
>and it cracked in pieces.
>I went back to the supplier who told me that that clay was discontinued.
>Apparently it didn't hold up under the cone 10-11 they had advertised
>it. It sure was a pretty red color, though. By the way no offer was
>made to compensate me. My daughter now has 9 plates to serve cold or
>warm dishes on. And I buy my clay from a different supplier.
>Cynthia Blau
>Fairfax, VA (now in Highland Beach, FL for the winter)
>
>
David Hendley
Maydelle, Texas
See David Hendley's Pottery Page at
http://www.sosis.com/hendley/david/
Dannon Rhudy on mon 12 jan 98
.........Uneven heating will cause the plate to crack, the same as
if
you put the plate on a heat source.
Do you think a plate should be able to pass the "steaming mashed
potatoes"
test? Anyone?........
Hmmmmm. One of those (many) things I've not thought about. I do
occasionally warm things on a plate/microwave, never had a
problem. Now I'll HAVE to think about it, David, and it is all
your fault. Mostly, I don't use the microwave for re-heating...
I'll try various plates on hand, them as fits inside, and report
back.
If you're asking if it is a necessity to produce a plate that
will work in a microwave - not if you say "don't microwave this
plate". Doesn't mean folks won't, though.
Dannon Rhudy
potter@koyote.com
At 06:21 PM 1/10/98 EST, you wrote:
>----------------------------Original
message----------------------------
>Ron:
>Your message about firing clay too high made me wince. I threw
17 large
>dinner plates for a set for my daughter (the extra 5 so I could
make
>them match.)
>She oo'ed and ah'ed when I gave them to her. Several months
later she
>called to tell me that l plate broke when she heated some food in
the
>microwave. How can that be?, I said. All of us potters are
telling our
>customers our work is "microwave, oven and dishwasher safe". The
next
>week another plate broke under the same circumstances. The next
week
>all she did was put an ear of corn from the steamer onto a third
plate
>and it cracked in pieces.
>I went back to the supplier who told me that that clay was
discontinued.
>Apparently it didn't hold up under the cone 10-11 they had
advertised
>it. It sure was a pretty red color, though. By the way no offer
was
>made to compensate me. My daughter now has 9 plates to serve
cold or
>warm dishes on. And I buy my clay from a different supplier.
>Cynthia Blau
>Fairfax, VA (now in Highland Beach, FL for the winter)
>
>
David Hendley
Maydelle, Texas
See David Hendley's Pottery Page at
http://www.sosis.com/hendley/david/
DONPREY on mon 12 jan 98
As you say, a microwave can quickly develop a concentrated area of high heat
if the food (read water content) is not evenly distributed. I never subject
my favorite plates or bowls to that kind of treatment. I reach for the pyrex.
Don Prey in Oregon
Dave Eitel on tue 13 jan 98
If we tell our customers our work is microwave safe, then it ought to be.
If it isn't, we should tell them that. My practice is to caution customers
not to place plates in a conventional or microwave oven, but I do it with
some of my plates. Occasionally one breaks. I've noticed it mostly with
plates having high iron glazes when the food on them was frozen. Boy am I
dumb!
Dave Eitel
Cedar Creek Pottery
Cedarburg, WI USA
http://www.cedarcreekpottery.com
Cindy on tue 13 jan 98
In regard to microwaves,
A friend asked me if microwaving pottery would tend to release heavy metals
more quickly. He said he heard that lead was more likely to leach in the
microwave. I never heard of this before, and I wondered if any of you have?
I don't, and wouldn't, use lead, but I like a small amount of manganese in
my blues. Does anyone know if the danger of using heavy metals is increased
by using pottery in microwave ovens?
Cindy in Custer, SD
Ron Roy on tue 13 jan 98
My feeling about this is they should be able to take that kind of
treatment. From looking at diatometer charts of many clay bodies I can see
why it would happen to some. Certain high fire bodies can have lots of
cristobalite in them - combine that with a glaze with a low enough
expansion and I can see why it would happen. This sort of thing should be
easy to test for. Freeze the plate overnight and pour boiling water on part
of it while it's still frozen. If it can take that I am sure it will
survive in a microwave - even under uneven conditions.
I can do a dilatometer test on clays and glazes - there is a cost involved
however.
>----------------------------Original message----------------------------
>Cynthia,
>I don't think you should expect to be able to heat food in a
>microwave on a large plate made with an ordinary stoneware body.
>
>Think about it.
>Say you plop a pile of mashed potatoes on one section of a plate,
>so about 1/3 of the plate has food on it and 2/3 of it does not.
>If you nuke it on high for a while the potatoes will get very hot.
>The heat from the food will transfer to the plate, but this will be
>concentrated on only one small area of the plate.
>Uneven heating will cause the plate to crack, the same as if
>you put the plate on a heat source.
>
>This is not a problem with a mug or a bowl because, since they
>contain liquid, the heat is evenly spread over the whole piece.
>
>I've never had anyone complain, but, being a cautious guy,
>I tell my customers that my plates can be used in the microwave
>IF the food is evenly distributed over the plate and a LOW to
>MEDIUM setting is used.
>
>That said, I do agree that your plates broke entirely too easily,
>and I hope your new clay does better.
>But, now I'm wondering what others think about this.
>Do you think a plate should be able to pass the "steaming mashed potatoes"
>test?
>Anyone?
Ron Roy
93 Pegasus Trail
Scarborough,Canada
M1G 3N8
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
Leslie Norton on tue 13 jan 98
I microwave food in plates and bowls all the time, don't remember ever
having a problem. Of course if the plate were very "uneven" in thickness, I
could see this might cause a problem. I am currently working on a
dinnerware design that I figure will be used in the microwave. Definitly
will run some extensive tests on this issue.
> -----Original Message-----
> From: Dannon Rhudy [SMTP:potter@koyote.com]
> Sent: Monday, January 12, 1998 10:28 AM
> To: Multiple recipients of list CLAYART
> Subject: Re: microwaving food on a plate
>
> ----------------------------Original message----------------------------
>
> ........Uneven heating will cause the plate to crack, the same as
> if
> you put the plate on a heat source.
>
> Do you think a plate should be able to pass the "steaming mashed
> potatoes"
> test? Anyone?........
>
> Hmmmmm. One of those (many) things I've not thought about. I do
> occasionally warm things on a plate/microwave, never had a
> problem. Now I'll HAVE to think about it, David, and it is all
> your fault. Mostly, I don't use the microwave for re-heating...
>
> I'll try various plates on hand, them as fits inside, and report
> back.
>
> If you're asking if it is a necessity to produce a plate that
> will work in a microwave - not if you say "don't microwave this
> plate". Doesn't mean folks won't, though.
>
> Dannon Rhudy
> potter@koyote.com
>
>
>
>
> At 06:21 PM 1/10/98 EST, you wrote:
> >----------------------------Original
> message----------------------------
> >Ron:
> >Your message about firing clay too high made me wince. I threw
> 17 large
> >dinner plates for a set for my daughter (the extra 5 so I could
> make
> >them match.)
> >She oo'ed and ah'ed when I gave them to her. Several months
> later she
> >called to tell me that l plate broke when she heated some food in
> the
> >microwave. How can that be?, I said. All of us potters are
> telling our
> >customers our work is "microwave, oven and dishwasher safe". The
> next
> >week another plate broke under the same circumstances. The next
> week
> >all she did was put an ear of corn from the steamer onto a third
> plate
> >and it cracked in pieces.
> >I went back to the supplier who told me that that clay was
> discontinued.
> >Apparently it didn't hold up under the cone 10-11 they had
> advertised
> >it. It sure was a pretty red color, though. By the way no offer
> was
> >made to compensate me. My daughter now has 9 plates to serve
> cold or
> >warm dishes on. And I buy my clay from a different supplier.
> >Cynthia Blau
> >Fairfax, VA (now in Highland Beach, FL for the winter)
> >
> >
> David Hendley
> Maydelle, Texas
> See David Hendley's Pottery Page at
> http://www.sosis.com/hendley/david/
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