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paperclay and mold, redux

updated mon 5 may 03


L. P. Skeen on sat 3 may 03

I have been using paperclay in my studio since December. I've had two =
kinds, both made with the patented paper fiber "invented" by Rosette =
Gault. One recipe had 30% paper pulp by volume in the recipe; the other =
had in the neighborhood of 10%. Both claybodies have developed mold on =
exposed surfaces (cut edges and the outside of pugs). The body with =
higher paper content also has developed mold WITHIN the pugs; it's =
slimy, and boy does it reek.

There has been some discussion here of is mold good or bad, will it hurt =
us or not. If you're using paperclay inside your house, it is possible =
that mold from the clay could infest the house itself. When your =
homeowners insurance renewed this year, you may have received a notice =
that your insurance company would not cover damage or health problems =
caused by mold. This is common in the insurance industry today, because =
of a lawsuit filed in Texas. There have been numerous reports in the =
media about people who've had to abandon their houses because of molds =
that make them sick just from being near them. Some molds are good and =
generally harmless; some are merely "bad", and some will kill you. =20

I had the mold on both paperclays and some paperclay slip tested by a =
biologist. He took samples of the clays and molds on sterile sponge =
things, tested clay pH, took the samples back to the lab and "plated" =
them to watch for mold colony growth. Here is a list of what molds he =
found on these clays, in no particular order. Some are relatively =
harmless; others are not. More of the "bad" molds were found in the =
clay with higher paper content. I will let you look these up for =
yourselves and make your own decision about whether you'd like paperclay =
to be in your studio. It's a marvelous material, but as for myself, the =
high paper-content clay is going out to the dump, and in the future, I =
will either make my own pulp (prolly with bleach in the water), or buy =
commercially made clays in small quantity so the mold thing does not =
become a big issue. I was going to ball up the hi-paper stuff and fire =
it for driveway rocks, but given the condition of my hands since I =
started working with it, I'm gonna pass. If YOU are working with =
paperclay, I suggest good-quality rubber gloves. (Don't buy the ones =
near the bandaids at Eckerd drugstore; they suck.)

Rhizopus stolonifer
Neurospora sitophila
Serratia Marcescens
Aspergillus Niger
Aspergillus sp.
Cladosporium macrocarpum

When the biologist took the samples, he mentioned in passing that clay =
was prolly the perfect pH for growing mold in the first place. This =
makes me wonder if we change the pH of our clay, say by adding vinegar =
to upset the balance, if we'd retard the mold growth in the first place, =
but I forgot to ask him. Also, he said that for MILD mold growth, the =
clay could be sprayed w/ bleach to kill it.

Anybody know Monona Rossol's email address? I'd like to send her this =

L. P. Skeen
Living Tree Pottery, Summerfield, NC
Get your copy of the 2003 Clay Lover's Calendar
at my website above! :)

Nanci Bishof on sun 4 may 03

When I attended a workshop Rosette Gault gave a several years ago she
recommended adding bleach water periodically to kill the mold. Sunlight helps