Crawling Varnish

¶ Crawling Varnish. This condition can readily be recognized by the fact that the varnish acts like oil on a wet surface. The varnish fails to attach itself to the surface in places and crawls or wrinkles or puckers up in tiny waves or folds.

¶ The cause of crawling is the application of varnish over surfaces which are wet, or greasy, or cold, or which have too high a gloss. Crawling,,may also occur when new varnish is put on over previous coats which are sweaty, which are not hard and dry. Dirty and sweaty finger marks on the surface before varnishing will cause crawling, the perspiration really is a greasy film. A film of soap left from washing without thorough rinsing with clean water will cause crawling. The addition of drier to varnish may cause crawling by making it dry too rapidly and before it has attached itself firmly to the surface. The practice of adding drier to varnish is a vicious habit and ruins good material. The manufacturer puts in the right kind and amount of drier when he makes the varnish and it is unwise for the finisher to add drier in his ignorance of the chemical actions involved. When two or more kinds of varnish are mixed together the finisher is inviting the appearance of crawling varnish. And when a can of varnish is allowed to remain uncorked until it becomes thick it may cause crawling if it is thinned with benzine instead of pure turpentine. Too much benzine will ruin any except the cheap rosin varnishes.

¶ Even the best of linseed oil ought not to be mixed with varnish,it may cause crawling. The use of an oil-soaked brush may cause it. Quick changes of temperature from warm to cold and of weather from dry to cold, foggy air, cold drafts, etc., are sometimes sufficient to cause crawling of varnish. Oil in the wood surface may cause crawling. Cypress contains a little natural oil on the surface and some finishers oil-coat wood to even up the suction, a good practice, before staining. But if these oily surfaces are not bone dry before varnishing the coat may crawl. The cypress surface can be wiped free from surface oil with a turpentine or benzole soaked cloth. When the surface is cold and the varnish is cold, either below 70 degrees, crawling is apt to occur. Poor workmanship in the brushing of varnish will cause the coating to crawl because it is a thick and thin job, that is, the varnish is not distributed evenly over the surfaces. In the places where the varnish is put on too thick it will crawl, wrinkle or pucker up. A thin film of wax on a surface left by the use of liquid varnish removers will cause crawling, fitting and cracking. The wax should be washed off with benzole or alcohol.

¶ A varnish having excessive body, too thick, may crawl, especially on a surface with a high gloss.

Next Page: Running, Sagging and Wrinkling Varnish.