Daisypet on wed 25 mar 98
Somewhere I have read that CMC can 'spoil' in solution in storage. Either in
solution by itself-using it as a medium for stains or as a suspending agent
in glazes. I also have read that it is an ingredient in some commmercial
glazes-and that it is the culprit that causes mold or some other breakdown.
Aren't there some preservatives or antiseptic type things to use?
I purchased a beautiful commercial glaze in quantity because I wanted to dip
my pots. I did not use it all,of course,and when I went back to it,the color
had changed and the smell was bad. The supplier was out of the dry glaze so I
had purchased liquid. This was several years ago,I have not had the problem
since but have wondered. Answers anyone? My supplier had no answers.
Phyllis Tilton
Daisypet@aol.com
Tom Buck on thu 26 mar 98
All cellulosic materials will be attacked by microbes/molds that like wood
cellulose, or cereal starches, for food. Depends on time, temperature,
concentration, aerobic or anaerobic conditions.
If your CMC containing slurry is relatively low on the compound
(proper name, sodium carboxy methyl cellulose, or Carboxy Methyl Celluose
sodium salt), then the alklinity of the slurry may be quite low and in
some cases may be neutralized by other components, and as a result the
microbes/molds may find the environment more to their liking.
I store CMC as a 3-5% solution and never have mold problems. So, I
suggest you add some Epsom Salts (MgSO4) to your glaze slurry, about 2 tsp
per gallon (2+g/Litre) and this may change the environment enough to stop
the microbes/molds from doing their thing. The Mg ion may also help keep
the slurry in suspension longer, and has little effect on the maturing of
the fired glaze. Til later.
Tom Buck ) tel: 905-389-2339 & snailmail: 373 East
43rd St. Hamilton ON L8T 3E1 Canada (westend Lake Ontario, province of
Ontario, Canada).
Buckner & Broyles on thu 26 mar 98
I have mixed solutions of CMC sit on the shelf for some years without any
apparent spoilage or degradation. -Bill Buckner (off to NCECA tomorrow!)
At 10:30 AM 3/25/98 EST, you wrote:
>----------------------------Original message----------------------------
>Somewhere I have read that CMC can 'spoil' in solution in storage. Either in
>solution by itself-using it as a medium for stains or as a suspending agent
>in glazes. I also have read that it is an ingredient in some commmercial
>glazes-and that it is the culprit that causes mold or some other breakdown.
e-mail: billtom@mindspring.com
web: billtom.home.mindspring.com
George Mackie on thu 26 mar 98
Phyllis - I put sodium azide in my CMC solutions- just a tiny pinch, less
than 0.5% stops bacteria cold turkey. George
Stephen Mills on thu 26 mar 98
CMC is an organic polymer. If kept in solution it will go "off". The
solution (pun intended) is to add some form of antiseptic solution to
it. We use a form of formaldehyde to prevent mould etc.
CMC is widely used in the food industry.
Shelf life in brush-on glazes is very variable, but most are relatively
short because they contain CMC which will break down eventually
Steve
Bath
UK
In message , Daisypet writes
>----------------------------Original message----------------------------
>Somewhere I have read that CMC can 'spoil' in solution in storage. Either in
>solution by itself-using it as a medium for stains or as a suspending agent
>in glazes. I also have read that it is an ingredient in some commmercial
>glazes-and that it is the culprit that causes mold or some other breakdown.
>
>Aren't there some preservatives or antiseptic type things to use?
>
>I purchased a beautiful commercial glaze in quantity because I wanted to dip
>my pots. I did not use it all,of course,and when I went back to it,the color
>had changed and the smell was bad. The supplier was out of the dry glaze so I
>had purchased liquid. This was several years ago,I have not had the problem
>since but have wondered. Answers anyone? My supplier had no answers.
>
>Phyllis Tilton
>Daisypet@aol.com
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Tom Buck on fri 27 mar 98
Sir: The chemical you cite, sodium azide, NaN3 (Na=sodium, N=nitrogen), a
colourless crystalline substance, should NOT be in any
potter's studio. It is highly toxic, and subject to unpredictable and
sudden release of gas with explosive force. Perhaps you can suggest other
safe bugkillers that will serve just as well.
Tom Buck ) tel: 905-389-2339
& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
(westend Lake Ontario, province of Ontario, Canada).
On Thu, 26 Mar 1998, George Mackie wrote:
> ----------------------------Original message----------------------------
> Phyllis - I put sodium azide in my CMC solutions- just a tiny pinch, less
> than 0.5% stops bacteria cold turkey. George
>
George Mackie on fri 27 mar 98
Tom - we use NaN3 routinely in our research work (immunocytochemistry) to
stop microbial decomposition of antisera, so it was one of the first things
to come to mind when I was looking for a bacteriocide to put in CMC
solutions. Cant say I have experienced the dire results you describe but if
what yoiu say is true I had better stop promoting it to the potter6y
community! Thanks for the tip. george
At 11:28 PM 3/26/98 -0500, Tom Buck wrote:
>Sir: The chemical you cite, sodium azide, NaN3 (Na=sodium, N=nitrogen), a
>colourless crystalline substance, should NOT be in any
>potter's studio. It is highly toxic, and subject to unpredictable and
>sudden release of gas with explosive force. Perhaps you can suggest other
>safe bugkillers that will serve just as well.
>
>Tom Buck ) tel: 905-389-2339
>& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
>(westend Lake Ontario, province of Ontario, Canada).
>
>On Thu, 26 Mar 1998, George Mackie wrote:
>
>> ----------------------------Original message----------------------------
>> Phyllis - I put sodium azide in my CMC solutions- just a tiny pinch, less
>> than 0.5% stops bacteria cold turkey. George
>>
>
>
>
Bill Amsterlaw on fri 27 mar 98
Hi George:
What is sodium azide and where do you purchase it?
- Bill Amsterlaw (wamster@slic.com)
Plattsburgh, NY
George Mackie wrote:
<< I put sodium azide in my CMC solutions- just a tiny pinch, less than 0.5% sto
Foresthrt on fri 27 mar 98
------------------
=3Epurchased a beautiful commercial glaze in quantity because I wanted to =
dip
=3Emy pots. I did not use it all,of course,and when I went back to it,the =
color
=3Ehad changed and the smell was bad. The supplier was out of the dry glaze =
so I
=3Ehad purchased liquid.
Did you use it anyway? I suspect that the glaze would still work, though
you'd=0Ahave to put up with the smell til it was fired. At about 500 =95F, =
all
the=0Aorganics should be burning out, and the glaze would be odor free =
again.
Mary Klotz=0A
Bonnie Staffel on fri 15 may 98
> ----------------------------Original message----------------------------
> Somewhere I have read that CMC can 'spoil' in solution in storage. Either in
> solution by itself-using it as a medium for stains or as a suspending agent
> in glazes. I also have read that it is an ingredient in some commmercial
> glazes-and that it is the culprit that causes mold or some other breakdown.
>
> Aren't there some preservatives or antiseptic type things to use?
>
> I purchased a beautiful commercial glaze in quantity because I wanted to dip
> my pots. I did not use it all,of course,and when I went back to it,the color
> had changed and the smell was bad. The supplier was out of the dry glaze so I
> had purchased liquid. This was several years ago,I have not had the problem
> since but have wondered. Answers anyone? My supplier had no answers.
>
> Phyllis Tilton
> Daisypet@aol.com
>
>Dear Phyllis,
I have been using CMC for about 30 years, making up washtub size gallons of glaz
t the bottom of the batch. I have discovered "Flocs" from Axner and it is a won
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