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Re: [teacherartexchange] Moldy Clay


From: Marvin Bartel (marvinpb_at_TeacherArtExchange)
Date: Tue Apr 05 2011 - 20:47:46 PDT

I had not heard of using vanilla to combat mold, but if it helps, why not? Does vanilla contain alcohol? Might alcohol reduce mold growth?

I once had two science students in class who identified the natural anaerobic bacteria in the clay. As the clay ages, the bacteria helps the plasticity of the clay. They identified the natural bacteria in the clay and tried adding nutrients to increase the bacteria count in order to increase the plasticity of the clay. I also remember grad students adding bear to their clay mix, but I had never heard of adding potato starch. My students tried bear, but they said the blended potatoes increased the bacteria growth much more than anything else that they tested. They thought it improved the plasticity. Unfortunately, the clay also got a lot of mold, was full of black streaks, and smelled quite bad. It was too much like garbage. Maybe they used too much potato starch. I think they put a package of instant mashed potatoes in about 150 pound of clay. I would not recommend it, but it might work with a very small amount of potato starch if vanilla (or bear) was also added. I have heard that the ancient Chinese potters kept clay moist in caves to allow it to age and become more plastic for their grandchildren to use.

On Apr 5, 2011, at 6:09 PM, pam smith wrote:

You are much better at this than I am. I too had smelly reclaimed clay and I
know to kill the smell of house paint I read to add a little vanilla to it. I
tried this with my clay and it really seemed to help with the smell at least.
Have you ever heard of using vanilla or anything else?

Just my two cents worth.

----- Original Message ----
From: Marvin Bartel <>
To: TeacherArtExchange Discussion Group <>
Sent: Mon, April 4, 2011 4:12:44 AM
Subject: Re: [teacherartexchange] Moldy Clay


I was a clay teacher for over 40 years. What you describe is common problem with
rework clay, and even with new clay that has been in moist storage for long
periods. In all my classroom years this a problem for only one student who
happened to have an allergic reaction to the mold. She was hypersensitive to
molds, and could not be in the room. For everybody else it was a bit smelly, but
to my knowledge it was never a health risk. I believe you can safely use the
clay. Some ventilation is always good. In my opinion, clay and glaze dust can be
a greater problem, but there are good ways to control those by using only wet
smoothing and wet cleaning methods. Avoid sanding, counter brushes, brooms, and
vacuum cleaners.
You can search Hazards in Ceramics and/or Cleaning and working with less clay
dust for more information.


On Apr 4, 2011, at 8:19 AM, Paternoster, Dana wrote:

I have a clay question. I have clay in my classroom that was bricks when I got
here six years ago, and that I have recently been reclaiming. I seems to be
molding very quickly. I may be mixing different kinds of clay together too.

It smells really bad, and I have been telling the kids that the clay is old, and
could be moldy and that is why it stinks. They are just grateful to get to use
it, and have not been complaining, but I am also not requiring them to use it,

Is there a way to kill the mold? It does not seem to be just on the surface,
but going through the clay. That is unless I have a grey clay mixed with the
other, but the grey parts of the clay stinks worse than the rest.

Am I in big danger of making us all sick?

I don't have money to buy new clay.

Thanks for your help.

Dana Paternoster
Visual Art Department
Seaford Senior High School
Seaford, Delaware
(302) 629-4587 ex. 248
Department Web Site

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