Q. I am an artist and am looking for a way to produce the skinning effect you get with some stored alkyd paints. I am looking for a low-cost, industrial, clear, glossy alkyd medium (base, varnish, etc.) product that will do the skinning effect for me. I have experimented with several alkyd mediums, and they dry without skinning when left to air dry. I understand the alkyd medium needs to be exposed to air in order to wrinkle like skin. That’s exactly what I need, as long as I can always repeat that effect with the same product. Can you please recommend a low-price medium that I can use for my art? I.S.
A. The term “medium” used by I.S. refers to a clear matte or gloss finish used by artists. It often is used as an overcoat as well as an extender to reduce the hiding power of an artist’s colors to get special effects.
Many paint manufacturers have been adding anti-skinning agents to paints for several years to prevent skinning, so it’s no wonder you couldn’t get your alkyd varnish to skin.
The best approach for you to get controlled skinning is to add a drier, such as cobalt napthanate, to an alkyd varnish. The reaction mechanism for curing alkyds resins is free radical polymerization, which results from contact with oxygen. Driers are organo-metallic compounds that catalyze and/or accelerate the polymerization of paint and varnish vehicles.