Ama Menec on tue 17 jan 06
I've always used Herculite plaster and never got this salts problem. Now
that I've changed to Prestia Creation it's happening to all my brand new
moulds. They are furry little beasties from about the second week of life;
same clay, same water supply. Don't know how to stop it! Any suggestions?
Ama, Totnes, Devon, UK.
John Rodgers on thu 19 jan 06
This is a consequence of sodium silicate slowly migrating through your
molds in the water that works it's way through your molds.
Not much can be done about it. But not to worry, doesn't hurt anything.
Just dust it off with a dry brush and get on with your work. This
usually doesn't happen until the mold reaches at least middle age. As
the mold approaches older age it gets really bad and layers will begin
to flake of the mold. At middle to old age, the molds need to be replaced.
Pushing the molds by casting more than once a day without drying in
between contributes this build up of fuzz.
Regards,
John Rodgers
Chelsea, AL
Teresa Griffin wrote:
>> HELP!!!!
>>
>> My tile molds are growing white fuzz. little little crystal formations.
>> They have been just fine for months and now. for some reason when i
>> go to
>> un mold the tiles from the mold the outside of the molds are caked with
>> this fine white fuzzy growth.
>>
>> I do not understand. Are my molds bad. I have tried to wash it off
>> and the
>> next time I use them they are fuzzy again.
>>
>> I use macky slip by the way.
>>
>> Teresa
>>
>>
>
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Fredrick Paget on thu 19 jan 06
> > HELP!!!!
>>
> > My tile molds are growing white fuzz. little little crystal formations.
>
> > Teresa
This is from the soluble soda ash and other stuff that comes in the
slip working on the plaster. It is fairly harmless and you can just
brush it off and continue to use the molds until they erode to the
point you are not satisfied with the results. Molds don't last
forever.
--
From Fred Paget,
Marin County, CA, USA
fredrick@well.com
http://homepage.mac.com/fredrick/FileSharing1.html
Charter Member Potters Council
skiasonaranthropos@FSMAIL.NET on fri 20 jan 06
Hello Teresa,
Sounds like it could be soluble salts from the water. The mould will draw
water from the clay body and towards the mould surfaces. The water will
evaporate and anything that was dissolved is left at the surface.
Stopping reoccurrence may be difficult as unless the level of salts
changes each time you use them you will be introducing more. But:
1. Dry the moulds after use ... not above 40oC or youll damage the plaster
2. Dont use too much water to wash the moulds, or again youll damage the
plaster
However if its not stopping making your tiles just wipe the surfaces every
time and carry on, though avoid contact with the tile surfaces as s.salts
will encourage glaze crawl
Regards,
Antony
William & Susan Schran User on fri 20 jan 06
On 1/20/06 12:00 PM, "Teresa Griffin" wrote:
> I do not understand. Are my molds bad. I have tried to wash it off and the
> next time I use them they are fuzzy again.
It's salts migrating to the surface, from the clay or the water.
I don't have a solution for you except to completely dry the plaster molds
and brush of accumulated salts.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
marianne kuiper milks on fri 20 jan 06
Have you tried firing them at a very low firing temp? I'd say maybe 350º F or even less should do it, or over 100º celsius. If you cannot fire them, try a mold-inhibitor, which you can get at pharmacies, paint stores, maybe even a good hardware/lumberyard outfit. Or boil in water for 3 minutes, depending on the material you use, and cool very slowly on a warmed towel.
Heat is one item that will kill mold, because (most) mold grows through moisture, I know you didn't sound concerned about the clay, but I doubt it will hurt the clay. I have used moldy clay and besides my nose everything else was fine, esp. after firing. (Choice of moldy clay or no clay at times)
Marianne
Teresa Griffin wrote: > HELP!!!!
>
> My tile molds are growing white fuzz. little little crystal formations.
> They have been just fine for months and now. for some reason when i go to
> un mold the tiles from the mold the outside of the molds are caked with
> this fine white fuzzy growth.
>
> I do not understand. Are my molds bad. I have tried to wash it off and the
> next time I use them they are fuzzy again.
>
> I use macky slip by the way.
>
> Teresa
>
>
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Teresa Griffin on fri 20 jan 06
> HELP!!!!
>
> My tile molds are growing white fuzz. little little crystal formations.
> They have been just fine for months and now. for some reason when i go to
> un mold the tiles from the mold the outside of the molds are caked with
> this fine white fuzzy growth.
>
> I do not understand. Are my molds bad. I have tried to wash it off and the
> next time I use them they are fuzzy again.
>
> I use macky slip by the way.
>
> Teresa
>
>
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