PITTING.
Pitting transforms a film of varnish into an expanse of minute indentations or pits, and simply represents in an aggravated form what is commonly known as pin-holing. The depravity is caused by a lack of uniformity in atmospheric conditions during the drying process, such as from warm to cold, dry to moist; mixing varnish of various grades; varnishing over a sweaty surface or over imperfectly dried color or varnish coats, or in an apartment having an excessively wet floor, or during a day of unusual moisture. Pitting may also come from varnishing over a surface rubbed through to the under coats. Varnish charged with gaseous impurities, or a varnish not sufficiently ripened, is powerfully inclined to pit. Dirty varnish, sometimes ditto. Soap or grease smears will cause pitting, as will also too oily under coats. Draughts of cold air have been known to cause bad cases of pitting.