Glossary of Finishing Terms

Atomization
The breaking up of finish particles through the tip of an air gun under pressure. A fine mist is created that lands on the surface and levels out to a smooth finish.

Binder
Finish or resin added to the stain, used to lock the pigment and dyes into the wood.

Blush
Cloudy haze in finish caused by moisture trapped beneath the surface. High humidity is the most common cause. Can be also caused by the improper application of an oil base stain under a water base finish.

Coalescing
The evaporation of the chemicals that keep the acrylic resin in a liquid form. Once this process is complete, the acrylic forms a hard finish film.

Crazing
Tiny cracks in the finish film, usually along the edges of a surface. Caused by the finish drying too fast in high temperatures.

Extender
Chemical additive used to control the drying and flow of water base finishes. Can be used with stains and finishes to "extend" the open time.

Fish Eyes
Defects in the finish film caused by surface contamination (usually from oils, silicones, and waxes.)

Gloss
The amount of light reflected off the finish surface. High gloss is rated 80-90° . Semi gloss is rated 50-75° . Satin is rated 30-45° . Rubbed effect is rated 20-25° . Flat sheen is rated 5-15° .

Grain Raising
Tiny fibers in the wood grain that lift when exposed to water. Easily controlled with proper sanding.

HVLP
(High Volume Low Pressure). An HVLP spray unit consists of a turbine motor that produces warm, low-pressure air. Its high transfer efficiency increases the square foot coverage.

Orange Peel
Defect in finish film usually caused by cool drying temperatures or improper fluid tip size. The finish looks like the surface of an orange.

Pinholes
Small defects in finish film caused by surface contamination. Resembles tiny holes in the finish.

Resin
The material that forms a hard film on the surface after the chemicals have evaporated. Acrylics and urethanes are the common resins used in water base finishes.

Satin
Finish that has had the gloss reduced to provide a softer sheen. A flattening agent made from fumed silica reduces the amount of light reflected by the surface.

Stain
A liquid mixture to color wood. Made of 4 parts: Vehicle (water or solvent), Colorant (pigments and dyes), Binder (resin), Additives (solvents to control drying).

Viscosity
The thickness of a fluid. This is used to determine flow rates for spray application. Usually measured with a #2 Zahn cup or #4 Ford cup. Viscosity can be decreased by using the appropriate thinner.