Instead of fighting this characteristic, many artists have developed techniques to take advantage of it. To prevent paint from drying out in storage, be sure not to place it near blowers or heaters. All plastic containers are slightly porous and allow a small amount of water vapor to escape. Also, it is critical to clean the threads of lids and jars. If paint accumulates on these surfaces, the tops will not seal properly and the paints will begin to dry out.
Some artists suggest spraying a small amount of water on top of the paint to keep the paint fresh.
When spraying, use distilled or de-ionized water to avoid contaminating the paint. Paints will stay quite well in most basements, but should not be frozen. Although most acrylic paints will sustain several freeze-thaw cycles, freezing is not advisable. Art Tools Clean Tools should be kept wet to keep paint from hardening on them. Avoid storing brushes with the bristles, or hairs, up.