guitar finishing: glossary

TYPES OF FINISHES   |   COLOR CHART   |   GLOSSARY   |   GALLERY

BASECOAT
In the case of metal flake, pearlescent and some other exotic finishes, a basecoat of a certain color is applied first to achieve a desired effect. For example: a red metal flake will have a deeper, more three-dimensional look if applied over a black basecoat.

CATALYZED FINISH
A two component coating comprised of resin and hardener. When the two are mixed together, a chemical reaction occurs, curing the finish. This reaction is called crosslinking. Once cured, a catalyzed finish is impervious to solvents.

CHECKING [a.k.a. COLD CHECKING]
Hairline cracks in a finish caused by expansion and contraction of the wood underneath. This is most commonly caused by extreme cold and sudden changes in extreme temperatures.

CLEAR COAT
A film of clear coating applied over the color coat (unless natural) to further protect the wood and determine the sheen of the finish. On a gloss finish the clear coat greatly deepens the shine.

COLOR COAT
The one or more coats in the finish process that contain pigment or dye.

CROSSLINK
A chemical reaction characterized by two different molecules linking to form one.

CURE
The process by which a finish hardens.

GLOSS
Having a highly reflective sheen. A mirror-like quality achieved by extensive polishing.

GRAIN FILLER
A solvent-based paste that is applied on porous woods such as ash or mahogany to level the surface for subsequent coats. Grain filler can be colored to achieve different looks. Dark brown or even black grain filler is commonly used on mahogany to accentuate the grain patterns.

LACQUER
A term used to describe a surface coating. It is often used alone in reference to nitrocellulose lacquer, but this is incorrect. Polyurethane is also a lacquer when used as a surface coating.

MIL
A unit of measure equal to 1/1000 of an inch or .001”.

PENETRATING OIL
A type of finish usually comprised of a mixture of oils that penetrate into the wood and leave little film build-up on the surface. This type of finish is not very durable and must be reapplied regularly to protect the wood.

POROUS
Full of pores or holes

SATIN
Having a dull sheen. It is synonymous with matte, dull rub. This quality reflects less light than does gloss.

SHEEN
The luster of a finish whether gloss or satin.

SHRINK
Solvent-based finishes appear to shrink into wood grain over time. This is caused by the further evaporation of solvents from the finish. A solvent-based finish can be fully dry to the touch and still curing or evacuating solvents.

SOLVENT
A fluid that is used to dissolve or dilute another fluid or solid. Some common solvents used in finishing are alcohol, VM&P naptha, acetone and MEK.

SOLVENT-BASED FINISH
A coating comprised of a solid dissolved in a solvent. The coating cures as the solvent evaporates and leaves the solid component. A solvent-based finish can be re-dissolved at any time by applying solvent. This type of finish can take weeks to fully cure.

SOLVENT RESISTENT
A coating that, once cured, is unaffected by solvents.

STAIN
A dye suspended in solvent that is wiped onto wood to color it. Stains are good for accenting figure in woods like quilted maple.