Practical Carriage and Wagon Painting / A Treatise on the Painting of Carriages, Wagons and Sleighs, Embracing Full and Explicit Directions for Executing All Kinds of Work, Including Painting Factory Work, Lettering, Scrolling, Ornamenting, Varnishing, etc., with Many Tested Recipes and Formulas

by M. C. Hillick

BLISTERS.

The varnish surface, dry or apparently so, when afflicted with little eruptions, after the fashion of pustules on the human cuticle, is said to have blistered. The disease is caused by moisture in the wood, exposure to the intense rays of the sun during the early days of service, or to the presence of oil or grease on the surface directly under the finishing coat or between any of the preceding coats of varnish or color. Soft under coats develop blisters, their development through this medium being in this wise: Coats of lead, heavy in body, and perchance a bit fatty or gummy, are applied to the surface. Such coats do not dry thoroughly. Oil in color coats tends to the same result. They deceive the workman, being apparently dry, but not really, when choked up under subsequent coatings. A surface so builded is eventually put into service and submitted to the sunlight. Warmed by the heat, these undried particles of color or lead quickly respond to the law of expansion. The varnish, supple and full of elasticity, instead of cracking and splitting into fissures, simply swells up with the paint. Fierce stove or steam heat causes blisters. A varnish blister, if not located upon a too prominent portion of the surface, may be reduced to a surface fracture easily overlooked, by puncturing with a needle and then pressing the rupture down with a wet sponge.