I recently found numerous white small tuffs of mildew or mold growing on my very dark pastels (dark brown/black/blue), with two pastel companies’ brands being most affected. My studio is in the gulf South, an area of high humidity and I run the air conditioner when It is warm and I am at the studio (not all the time). I need to figure out why it seems that only the darks are getting this growth ….is it the possibly the preservative used, why mostly these two companies, why just the darkest darks, and most importantly, how do I systematically tackle the systematic cleaning of the pastels in a relatively safe manner. I can send images, if that is possible.
I find that certain natural earth colors ground into aqueous pigment pastes readily grow mold while others do not. Perhaps this has to do with spores already in the pigments or other materials attractive to mold/mildew? I will forward this to some experts in pastels in the hopes that they can shed some light on this.
Ivory black (calcined bone) can develop mold colonies in water-based products, even when preservatives are used. I’ve wondered for a long time whether dark colors in general might also provide a more favorable growth environment by reducing UV light exposure compared to highly reflective colors, but I think the main factor is whether the pigment (or another ingredient) is “mold food”.
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