Paul Lewing on sun 1 apr 07
On Apr 1, 2007, at 5:50 AM, Sandy Fenstermacher wrote:
I have a question about mold spots on the back of some tiles. They
are commercial tiles that some lady got on her trip through Europe,
and she wants them set and framed to hang.
Firing them would definitely get rid of it. You don't have to fire
them very high. If you have a 018 cone around for luster firings,
that would do it. If you don't have one, just put in any cone, get
it up past red heat, and turn it off. The actual temperature is not
critical at all. Actually if you get it up past 500 or 600 F that
should do it, and that's not even red heat.
Paul Lewing
www.paullewingtile.com
Sandy Fenstermacher on sun 1 apr 07
I have a question about mold spots on the back of some tiles. They are commercial tiles that some lady got on her trip through Europe, and she wants them set and framed to hang. The thing is that they were kept somewhere damp for.. awhile and now they have mold spots on the back. The guy who is making the frame told me he spot cleaned the mold with watered down bleach, but they keep returning. Any advice for getting rid of the mold for good before I set them?
Thanks : )
Sandy
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WJ Seidl on sun 1 apr 07
Sandy:
Bleach does NOT kill mold, it simply whitens it, makes it less noticeable.
Clean the tile with ammonia and water first, let it dry. Once it is dry,
THEN bleach it to remove the stain.
DO NOT do this if the tile body is not vitrified, it will leach salts from
the clay body and you will have efflorescence problems.
Best,
Wayne Seidl
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Sandy
Fenstermacher
Sent: Sunday, April 01, 2007 8:51 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: mold on tiles
I have a question about mold spots on the back of some tiles. They are
commercial tiles that some lady got on her trip through Europe, and she
wants them set and framed to hang. The thing is that they were kept
somewhere damp for.. awhile and now they have mold spots on the back. The
guy who is making the frame told me he spot cleaned the mold with watered
down bleach, but they keep returning. Any advice for getting rid of the
mold for good before I set them?
Thanks : )
Sandy
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The Goodsons on sun 1 apr 07
Hi all,
I have an additional question about mold. I have some plates that I
made about 5 years ago, so I know the clay and the glaze. Now, I
believe that they were underfired - would that have caused the mold?
(Also the thermal expansion on the glaze was far too low- maybe that was
a culprit as well?) I am thinking that refiring them would not only
kill the mold, but help it from coming back. I would appreciate any
thoughts.
Good day,
Linda Goodson
Lincolnton, NC
Matthew Katz on sun 1 apr 07
Hi,
So, I don't know if you know the vitrifaction test for clay. It is extremely
scientific and it is a great way to tell if work is porous. Lick it. I know
totally gross, especially If you feel like the is mold growing, but have
some Listerine ready to go as soon as you do it. It is a really good
indicator If the work is not fully vitrified, If you tongue sticks a little
if it is not vitrified. Otherwise, your tongue will slide off and leave a
little pool.
There is a good chance that the porous exposed areas (the foot) could
absorb material to breed mold or other bacterium.
Re-firing would kill the mold, although I don not know if it would leave a
residue inside the ware (I assume not). To completely eliminate the problem,
you would have to fire the work until vitrified. If you know the clay and
glaze, than it is a judgment call if they can take the increased temperature
needed to vitrify the work.
I doubt the glaze was the problem. This is pretty much a clay problem.
Best,
Matt
Good Luck
On 4/1/07, The Goodsons wrote:
>
> Hi all,
> I have an additional question about mold. I have some plates that I
> made about 5 years ago, so I know the clay and the glaze. Now, I
> believe that they were underfired - would that have caused the mold?
> (Also the thermal expansion on the glaze was far too low- maybe that was
> a culprit as well?) I am thinking that refiring them would not only
> kill the mold, but help it from coming back. I would appreciate any
> thoughts.
> Good day,
> Linda Goodson
> Lincolnton, NC
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
--
Matthew Katz
Alfred, NY
The Goodsons on sun 1 apr 07
Thanks, Matt,
I had many other plates and bowls from the same firing with no mold- so
I tried the tongue test. (cough, cough :-) !) They seem completely
vitrified. I will refire one and see what happens. I no longer use
that clay, and nothing else has any mold. So if it was a clay problem
that is a good thing.
Thanks so much,
Linda
Matthew Katz wrote:
> Hi,
> So, I don't know if you know the vitrifaction test for clay. It is
> extremely
> scientific and it is a great way to tell if work is porous. Lick it. I
> know
> totally gross, especially If you feel like the is mold growing, but have
> some Listerine ready to go as soon as you do it. It is a really good
> indicator If the work is not fully vitrified, If you tongue sticks a
> little
> if it is not vitrified. Otherwise, your tongue will slide off and leave a
> little pool.
> There is a good chance that the porous exposed areas (the foot) could
> absorb material to breed mold or other bacterium.
> Re-firing would kill the mold, although I don not know if it would
> leave a
> residue inside the ware (I assume not). To completely eliminate the
> problem,
> you would have to fire the work until vitrified. If you know the clay and
> glaze, than it is a judgment call if they can take the increased
> temperature
> needed to vitrify the work.
> I doubt the glaze was the problem. This is pretty much a clay problem.
> Best,
> Matt
> Good Luck
>
marci Boskie's Mama =^..^= on mon 2 apr 07
>Linda Goodson wrote:
>Hi all,
>I have an additional question about mold. I have some plates that I
>made about 5 years ago, so I know the clay and the glaze. Now, I
>believe that they were underfired - would that have caused the mold?
>(Also the thermal expansion on the glaze was far too low- maybe that was
>a culprit as well?)
Dont know if this helps or not, but with porcelain , if it is fired too
quickly or not hot enough , mold- like grey or black spots can appear in
the ware when it is painted with china paints and refired to
overglaze temps ( cone 018 -015 ) ... ( the " mildew" doesnt appear until
the piece is low fired ) Refiring it to about a cone 011 usually takes
care of it... and sometimes refiring it to overglaze temps ( 018 - 015
) several times also does it..The spots will happen on either glazed
or unglazed ware... It also happens on bone china that has allowed
to pick up moisture though the dry foot . ( remedy there is
usually scraping the dry foot to open the pores and refiring ) ...
Marci Blattenberger Boskie's Mama =^..^=
http://www.marciblattenberger.com
marci@ppio.com
Porcelain Painters International Online http://www.ppio.com
--
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The Goodsons on mon 2 apr 07
Hello, Marci,
Thank you for your reply. It is very helpful. I am going to refire!! I
will be happy to get rid of all that mold.
Sincerely,
Linda
marci Boskie's Mama =^..^= wrote:
>
>
>
>
> Refiring it to about a cone 011 usually takes
> care of it... and sometimes refiring it to overglaze temps ( 018 - 015
> ) several times also does it..The spots will happen on either glazed
> or unglazed ware... It also happens on bone china that has allowed
> to pick up moisture though the dry foot . ( remedy there is
> usually scraping the dry foot to open the pores and refiring ) ...
>
> Marci Blattenberger Boskie's Mama =^..^=
> http://www.marciblattenberger.com
> marci@ppio.com
> Porcelain Painters International Online http://www.ppio.com
>
>
> --
David Berg on mon 2 apr 07
Sandy,
You should not even have to "fire" the tiles in a kiln in order
to kill the mold and any spores. A regular oven will work. 3
hours at 300 degrees Fahrenheit (about 150 centigrade) will
sterilize the tiles of all mold + spores, bacteria and viruses.
Bleach is effective at killing bacteria and viruses and it will
also kill mold on non-porous surfaces. The mold on your
tiles keeps coming back after the bleach treatments because
the surface is porous and the mold's "roots" (mycelium) have
grown into the clay. The ionic structure of bleach (sodium
hypochlorite) prevents it from penetrating into porous surfaces
such as wood or non-vitrified clay. Laundry bleach is 99%
water. When one uses bleach to treat a porous surface,
the sodium hypochlorite stays on the surface and kills the
mold there while the water soaks into the clay and actually
helps the embedded mycelium to start to grow back again
after the bleach is gone.
So anyway, the simplest thing to do is to just bake your tiles
in the oven for three hours at 300 degrees Fahrenheit. Then
keep them dry and the mold should not come back.
David
David Berg
dberg2@comcast.net
http://bergstoneware.com/
On Apr 1, 2007, at 8:50 AM, Sandy Fenstermacher wrote:
> I have a question about mold spots on the back of some tiles. They
> are commercial tiles that some lady got on her trip through Europe,
> and she wants them set and framed to hang. The thing is that they
> were kept somewhere damp for.. awhile and now they have mold spots
> on the back. The guy who is making the frame told me he spot
> cleaned the mold with watered down bleach, but they keep
> returning. Any advice for getting rid of the mold for good before
> I set them?
>
> Thanks : )
>
> Sandy
>
>
> ---------------------------------
> Finding fabulous fares is fun.
> Let Yahoo! FareChase search your favorite travel sites to find
> flight and hotel bargains.
>
> ______________________________________________________________________
> ________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
Sandy Fenstermacher on tue 3 apr 07
YAY! Thank you so much for the helpful info. I was hoping I would be able to do something like that since I have not fired the kilns here yet. (I'm on an army base, and the kilns havn't been used since about '93) So I wanted to be able to get these taken care of without having to take the time for all the test firing/ kiln repair and what-not. I'm sure I'll be back with kiln questions soon. haha
Thanks again!
Sandy
David Berg wrote:
Sandy,
You should not even have to "fire" the tiles in a kiln in order
to kill the mold and any spores. A regular oven will work. 3
hours at 300 degrees Fahrenheit (about 150 centigrade) will
sterilize the tiles of all mold + spores, bacteria and viruses.
Bleach is effective at killing bacteria and viruses and it will
also kill mold on non-porous surfaces. The mold on your
tiles keeps coming back after the bleach treatments because
the surface is porous and the mold's "roots" (mycelium) have
grown into the clay. The ionic structure of bleach (sodium
hypochlorite) prevents it from penetrating into porous surfaces
such as wood or non-vitrified clay. Laundry bleach is 99%
water. When one uses bleach to treat a porous surface,
the sodium hypochlorite stays on the surface and kills the
mold there while the water soaks into the clay and actually
helps the embedded mycelium to start to grow back again
after the bleach is gone.
So anyway, the simplest thing to do is to just bake your tiles
in the oven for three hours at 300 degrees Fahrenheit. Then
keep them dry and the mold should not come back.
David
David Berg
dberg2@comcast.net
http://bergstoneware.com/
On Apr 1, 2007, at 8:50 AM, Sandy Fenstermacher wrote:
> I have a question about mold spots on the back of some tiles. They
> are commercial tiles that some lady got on her trip through Europe,
> and she wants them set and framed to hang. The thing is that they
> were kept somewhere damp for.. awhile and now they have mold spots
> on the back. The guy who is making the frame told me he spot
> cleaned the mold with watered down bleach, but they keep
> returning. Any advice for getting rid of the mold for good before
> I set them?
>
> Thanks : )
>
> Sandy
>
>
> ---------------------------------
> Finding fabulous fares is fun.
> Let Yahoo! FareChase search your favorite travel sites to find
> flight and hotel bargains.
>
> ______________________________________________________________________
> ________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
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