Sign makers often turn to stain because of its gentle chemical makeup which allows wooden signs to receive air. Being porous essentially erases the problem of blistering due to trapped water. Stain also comes in an array of qualities. However, the premium brands have the advantage of oil and nutrients that preserve the life of the wood even longer. After the application of paint or stain, sign workers must decide whether or not to apply varnish to the sign.
Varnishes add gloss to the surface of the sign and prevent the chipping and wearing away of paint.
Depending on the quality of the paint used on the sign prior to the varnishing stage, varnish is sometimes imperative. Although, many acrylic-based ultraviolet inhibitors are increasing the longevity of varnish, the standard types only last for approximately one year in an outdoor environment. Varnish may need to be applied on more than one occasion. These clear layers are chemically composed of solvents that are found in paint and stain, mixed with resins derived from tree sap. This mixture of ingredients is responsible for the decomposition of varnish in outside weather.