Paulette Carr on wed 1 sep 04
I am having some trouble with my glazes vis a vis, storage. I usually make
them up in small batches (300-500g), and all contain VeeGum Cer and glycerin
for brushing. Unfortunately, some of them grow mold, even in as little time as
1 month. I cannot tell which ingredients are the culprits, and it is not
predictable. I can make up a glaze at one time and find mold ... same glaze made
again, no mold. Mold doesn't grow in every glaze ... maybe only 20-30% of
what I prepare. I thought that maybe my storage containers were to blame (yogurt
and sorbet containers), so I now use new storage jars which are pre-washed in
hot water and detergent. Even in these containers, I find mold growing. If
I add enough bleach to kill the mold, then I disturb the thixotropic mixture,
and no telling, but that the mold has been feasting on the CMC and glycerin,
altering the brushing and dried surface quality of the glaze. I never notice
mold growing in the commercially prepared low-fire glazes I have -- some for
many years -- and supposedly they contain a great deal of gum. I am looking for
a preservative. I have a bottle of formaldehyde, but that never really
worked with the CMC gel. Does anyone have any experience solving this problem?
Someone suggested sodium benzoate. Does anyone use this, and if so, at what
concentrations? Do you have a source? It seems that I should be able to keep a
tightly closed glaze longer than 1 month or two. Any help would be
appreciated.
My best,
Paulette Carr
Paulette Carr Studio
Member/Potters Council
St. Louis, MO
Hank Murrow on wed 1 sep 04
On Sep 1, 2004, at 2:42 PM, Paulette Carr wrote:
> I am having some trouble with my glazes vis a vis, storage. I usually
> make
> them up in small batches (300-500g), and all contain VeeGum Cer and
> glycerin for brushing. Unfortunately, some of them grow mold, even in
> as little time as 1 month. I cannot tell which ingredients are the
> culprits, and it is not
> predictable.
Dear Paulette;
I use Vee Gum T, which doesn't contain the CMC component, and find that
it does not grow mold as readily. However, some glazes which contain
Bone Ash (of bovine origins) will grow mold. Look for bone ash in your
glazes & switch to Vee Gum T.
Cheers, hank in Eugene
murrow.biz/hank
William Melstrom on wed 1 sep 04
I believe that CMC, or other gums, are the main mold-producing culprits, but
clay, and other glaze materials also contain organics that will spoil.
I don't know why formaldehyde doesn't work for you, it works like magic for
me. Maybe you should try it again. I use about one ounce of 37%
formaldehyde in about 2 1/2 gallons (half a bucket) of prepared glaze.
Beware, formaldehyde is extremely nasty, but I'm willing to put up with it.
Ventilate well.
The only other solution that I know that works, is to refrigerate your
glazes.
William Melstrom
Austin, Texas
www.handspiral.com
Even in these containers, I find mold growing. If
> I add enough bleach to kill the mold, then I disturb the thixotropic
mixture,
> and no telling, but that the mold has been feasting on the CMC and
glycerin,
> altering the brushing and dried surface quality of the glaze. I never
notice
> mold growing in the commercially prepared low-fire glazes I have -- some
for
> many years -- and supposedly they contain a great deal of gum. I am
looking for
> a preservative. I have a bottle of formaldehyde, but that never really
> worked with the CMC gel.
Linda Ferzoco on wed 1 sep 04
I can't answer you main question about a preservative but please be
careful with formaldehyde; it's nasty.
http://www.merck.com/mrkshared/mmanual/tables/307tb3k.jsp
If memory serves me correctly, recent data show that it's also a
carcinogen. See this site: http://ehp.niehs.nih.gov/roc/toc10.html
Linda Ferzoco
Pacifica, California
--- Paulette Carr wrote: I
> am looking for
> a preservative. I have a bottle of formaldehyde, but that never
> really
> worked with the CMC gel.
Bill Karaffa on wed 1 sep 04
Try adding a little bleach to your glaze.
Bill Karaffa
Firemouth Pottery and Gallery
http://fp1.centurytel.net/karaffa
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