Studio Craft: Using Oil Paint that has Skinned Over

Ask the Expert: "Is it OK to use oil paint that has skinned over? I hate to throw it away if it's still good."

A: Watercolor and gouache can be reconstituted even if they have dried hard, but oil paint is different. Oils don't just dry through evaporation. Drying oils form solids as they oxidize, a process that starts as soon as paint leaves the tube.

Oil paint is at peak strength and adhesive power when it is fresh. Strictly speaking, oil paint that has partially dried has diminished in quality compared to wet paint from the tube. Artists tend to be thrifty, however, and there is often a natural inclination to salvage the usable portion of colors left on the palette.

Fast-drying colors like raw umber can skin over quickly, sometimes in as little as a day. Recently dispensed paint that has formed a skin, while not at optimal quality, is likely still usable.

Especially if the painting medium includes an oil or alkyd that reinforces film strength, it's unlikely any problems will occur as a result of using paint that has skinned over.

To retrieve fresh paint from dried piles, use a sharp knife to slice open the skin. Use a small palette knife to open the pile and examine the condition of the material inside. If the paint beneath the skin appears to be soft and pliable, transfer it to a clean palette. Paint that is stiff or rubbery should be discarded. Be careful not to mix any bits of dry material into the wet paint.

Paint that has been salvaged in this manner should be used up promptly, and should not be saved after a skin forms over the remainder.

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