One of the most commonly-heard complaints about working with acrylics is that they dry out, and dry out fast. You could be working on a painting, really getting into it when… whoops! That color you put on your palette thirty minutes ago has already solidified. And with the price of paint and the stress of re-mixing the same colors, you might be looking for a longer-lasting solution.
Art Advice: Making an Everlasting Paint Palette
1