Yellowing: Development of a yellow cast in aging paint; most noticeable in the dried films of white paints or clear varnishes. Possible causes: Oxidation of solvent-based paint or varnish. Heat from ovens, radiators and heating ducts. Lack of light (e.g., behind pictures or appliances, inside cupboards, etc.). Remedy: Top quality water-based paints do not tend to yellow, nor does non-yellowing varnish.Solvent-based paints, because of their curing mechanism, do tend to yellow, particularly in areas that are protected from sunlight.