• (p. pr. & vb. n.) of Curtain
In painting and decorating, curtaining refers to the occurrence of sagging or 'curtains' in paint, enamel or varnish films applied to vertical surfaces and being due to uneven application, and which manifests itself in the formation of thick lines of paint resembling a slung curtain.Curtaining is painting and decorating slang for sagging in paintwork, enamel or varnish giving the appearance of curtains.