In addition to additives, several techniques will help keep paints wet on the palette. A most important first step is to use a non-absorbent palette. Glass works nicely, as do plastics such as polyethylene. Glass stays fresh and free from stains, cleans easily and works well as long as it doesn't break. The problem with a glass palette tends to be the weight.
Many artists construct their own glass-topped taboret to use with acrylic paints.
On wheels, the glass palette is portable and the artist can use larger plates of glass without worrying about excess weight or breakage. To slow the drying of paints on glass or plastic palettes, use a small amount of retarder. About three to ten percent of Golden Retarder will keep a mass of paint from forming a skin for up to six hours, depending on the atmosphere. Excessive quantities of retarder, especially when working in thicker impasto, will leave the paint skin feeling like soft gum, as the glycol may not totally release from the film. Some people prefer to lightly mist the paint on their palettes.