Back in the old days, when I worked as an artist technical consultant at M. Grumbacher, my boss, the chief chemist who formulated our line of Hyplar acrylic paints, was very wary of adding extra water to aqueous emulsion systems. He also felt that a good storage practice to reduce mold would be a light spray of Lysol onto the top of the paint surface before closing jars and after scraping off any fungal growth, if detected. (Lysol in those days contained a fungicide called orthophenol-phenol, if I remember correctly. We used store acrylic paints in glass jars with regular threads and always wiped off the glass to make sure no wet color got trapped as the standard metal/ resin coated lids were tightened. A band of black electrical tape was wrapped around the seam and then a band of scotch tape over the electrical tape finished the job. Nowadays, storage within a Ziplock polyethylene bag could easily replace the need for taping the container. But I will emphasize that adding water directly to the acrylic paint mass could encourage the growth of mold over time. Of course if you use up the slightly thinned material in a few weeks it should be an issue. I have glass jars with metal lids which were prepped as I described above with electrical tape that contain paint we manufactured in the mid 1980's . The paint is in excellent condition to this day. The material I am describing was formulated with Manganese Blue pigment (Barium manganate). I have similar samples of Cerulean Blue (Cobalt stagnate) in similar excellent shape after nearly thirty three years in storage. I used both paints as recently as last month!
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> On Feb 3, 2019, at 2:17 PM, Lynette Cook <[log in to unmask]> wrote:
> One thing I do with both gesso and containers of paint is to take a small water spray bottle - such as a travel container (the water particles are nice and small) - fill it with distilled water (to help avoid mold issues), then lightly spray the water into the jar before putting the lid back on. It helps keep a humid environment so that the paint and gesso stay moist over time, even the part near the lid. It isn’t a perfect solution that lasts forever, but it does help and I seldom have the cracking/chipping issue.
> Lynette Cook
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