Interesting about the caution regarding water. This is true with distilled water also? I know tap can be an issue. When I find mold on my paint or gesso (and it’s rare) it tends to be a container that I have contaminated by putting my paintbrush inside (i.e. wet brush that had been in the tap rinsing water). I fill all my spray bottles with distilled, so it’s tap only in my brush rinse. I usually remember to put only a clean, dry palette knife or other utensil in the containers.

Lynette