A film on the surface of an oil painting that has been improperly varnished or stored, it first appears as an opaque blue tinge, which turns white, yellow, and eventually black as the condition, sometimes known as a &#39;chill, advances. Source: Kimberley Reynolds and Richard Seddon, "Illustrated Dictionary of Art Terms"<br><br>A dull, progressively opaque, white effect caused on varnished surfaces by damp conditions.<br><br>A fine cloudy discoloration which forms, most commonly, on the surface of varnish, or on melted wax or concrete cast in a plaster mold.