Chris Schafale on wed 3 nov 99
I understand CMC can go "off" or decompose in a glaze over time. If
this happens, what are the consequences? Just a bad smell? CMC no
longer doing what it was put there to do? Glaze otherwise affected?
I have about 15 gallons of a glaze that had CMC added and now smells
funny. Can I go ahead and use it as long as I can stand the smell?
Thanks for any help.
Chris
Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
Paul Stubbs on sat 6 nov 99
In message <199911021648430.SM00052@default>, Chris Schafale
writes
>----------------------------Original message----------------------------
>I understand CMC can go "off" or decompose in a glaze over time. Thanks for
>any help.
>
>Chris
>Light One Candle Pottery
>Fuquay-Varina, NC
>candle@intrex.net
Hello Chris from a new Clayarter in Somerset UK.
These CMC materials are everywhere there are even food and medical
grades. They are extremely versatile and have many uses to us potters
too.
If you create the right conditions then bacteria will help themselves to
this food source. I have used "Courgel and now "Finnfix". And both will
"go off" given the right conditions, the end result is a dark foul
smelling dirty grey slime in which the CMC will be rapidly losing its
binding and suspending properties, especially if you live in a warm
climate. The glaze will still be OK though but may be thinner or keep
dropping out of suspension or be less well bound together in the unfired
state.
You can stop it in the first place by adding a weak formalin type
bactericide such as Nuocept. or "Glokill".I suggest about 60 grams per
gallon of glaze if you are using a high concentration of CMC.
You may concider looking at wallpaper pastes such as "Polycell" they
are very similar and may incorporate fungicides, but read the heath and
safety info on the packet first, you might be put off that idea.
I am not sure if you can treat the problem once it has taken hold.
Good luck.
--
Paul Stubbs
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