One of my gifts this year for Christmas was clay and sculpting tools. I was really looking forward to letting my imagination run wild until I opened the box containing the clay and discovered what looked to be black mold growing on one side of the clay cube.
I presumed at first that the mold was an issue and was planning on exchanging the clay on the 27th when I decided to check online to see if this sort of thing happens a lot. I’ve since read some contradictory statements; some claim that moldy clay is fine if not good, while others claim that mold can / does pose serious health risks (obviously).
I’m hoping that there may be some artists on QT3 who have experience in working with clay who can help inform me on my moldy clay situation.
Q: I am an elementary art teacher. I need to know what can prevent mold from growing on the clay. I have a bucket lined with two bags, and it is always covered. I have heard Epsom salt is a better alternative than vinegar, but would like some advice. –K.M.
A: I have been a potter for over 40 years now and I always welcome that smell when I open a box of clay. It means the clay has “aged” – enough time has passed between the mixing of the clay and its use for bacteria and mold to develop. This is a good thing, because mold and bacteria contribute to the workability of the clay.
The way these by-products of the aging process contribute to workability is by increasing the flocculation of the clay body. This means that the clay particles will stay together better. Handles and other attachments will stick on better and the clay has less of a tendency to crack. The clay’s strength, plasticity, and resistance to stress are improved. Some potters even add some of their aged clay to freshly mixed batches to get the new clay to produce bacteria and mold faster than it would if left on its own.
My answer to your question is: Welcome that smell! Whenever you smell it, it means that your job as a potter has just become easier.
Some clay makers will occasionally add vinegar to clay to improve its workability. However, if clay that has had vinegar added is not used within a few weeks, then the smell can get to be too much. I don’t recommend it at all, because if you are trying to get rid of the smell, this will make it worse in the long run. Epsom salts will not cause the strong odor associated with vinegar, but will have the beneficial effect of helping to flocculate the clay body. Keep in mind that clay may contain bacteria anyway, and Epsom salts will not prevent their growth.
There are some individuals who are allergic to molds and mildew. They should not be around clay to start with. If aged clay is making anyone sick, and for some reason they have to be there, I suggest using bleach to cut down the bacterial and mold activity. This is not the best solution, because chlorine has its own drawbacks. Perhaps a few drops of diluted bleach in the bucket now and then might be a solution, but it might cause reactions more than the mold or bacteria. I certainly would not use bleach unless I absolutely had to.
In the end, my suggestion would be to get used to the moldy smell. Or, do as most potters do – welcome it!
Brighton, Ontario, Canada
Sounds like its normal and desired on natural clay.
This isn’t true. There are dangerous molds out there, whose problems, though exacerbated by allergies, will still harm people exposed to it nonetheless. Whether this clay could harbor such molds in unknown to me, but that doesn’t mean there aren’t harmful molds to watch out for. There’s a reason, beyond mere allergies (and hysteria), that mold inspections are becoming the norm when buying/selling property in certain parts of the country.
This isn’t true. There are dangerous molds out there, whose effects (not limited to allergic reactions, though exacerbated by such allergies), will still harm people exposed to it over a period of time. Whether this clay could harbor such molds in unknown to me, but that doesn’t mean there aren’t harmful molds to watch out for. There’s a reason, beyond mere allergies (and hysteria), that mold inspections are becoming the norm when buying/selling property in certain parts of the country.
That’s a mold deliberately grown for eating. There are in fact different kinds of mold, they produce different toxins and some can invade the human body. You do not want to eat mold that grows even on cheese where it wasn’t intended, either.
Yeah, yeah, I’m aware of all this. But the world is just filled with mold. You’re breathing in all kinds of spores all the time, and other kinds of mold are growing on your skin right now, even if you can’t see it. Harmful mold is quite rare. On average any random mold you see is just a superficial growth that will harm nothing. It’s like, I don’t know, bugs. Some insects are dangerous, but most aren’t, and if you find a random fly in your house, you don’t burn it down unless possibly if you are a redditor.
It’s not particularly likely that the mold on clay would hurt you… generally, because you aren’t made of clay.
Things that are dangerous are usually the things which are growing on stuff that you are made of… things which would find your body to be a hospitable place to live. I can’t see something growing on clay to fall into that category.