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Glossary of Log Home Maintenance Terminology

Brushing the stain or finish to ensure an even, thorough coat, while working the finish into the wood surface. Brushing the wet finish after spraying does this. Back-brushing can be done with a good quality paintbrush or with a painters pad. Always brush with the grain.

A color change phenomenon that occasionally takes place, most often during drying of a newly applied finish. It is an unusual, temporary color that a semi-transparent finish may take on while it is drying. Some finishes may also blush when they become water saturated.

The practice of mixing individual containers of finishes to help eliminate color variations that may exist. Color variations may come from inconsistent mixing procedures at the jobsite.

Brown Rot:
Predominate type of decay fungi that occurs in softwoods used above ground. Brown rot fungi attack the cellulose rather than the lignin. Brown Rot causes rapid degradation of the structural integrity and strength of logs. As the decay progresses, the wood appears to turn brown, often appearing as if it has been charred. In advanced stages, wood crumbles and voids form.

Term used to describe any strongly alkaline material, which is corrosive to living tissue and wood. Caustic liquids cause a very high pH in wood. Wood substrates exposed to high pH may release excessive tannins, sometimes causing darkened wood. High pH in the wood surface can lead to premature finish failure if not properly neutralized.

Chemical Stripping:
Removal of old finishes using liquid chemicals that soften or break down the finish to be removed. Chemical strippers are applied to the old finish surface and then removed, usually using pressure washing. Checks: Longitudinal splitting along the wood grain as wood seasons. Checks can provide a route for water entry deep into the wood, which sets up an environment conducive to decay.

Corn Blasting:
Removal of old finishes using modified sand blasting equipment. The finish is removed using ground corncob grit. Corn grit is less damaging to log surfaces and affords easier clean up than sand. Since this process involves no use of water, it leaves log surfaces dry and ready for immediate refinishing.

Cure time:
Cure time is the time that it takes for the finish to develop all of its protective properties, including hardness, UV resistance and water resistance. Cure times are longer than drying time and depend on temperature, humidity, thickness of coating and the type of coating.

Dry Rot:
A term loosely applied to dry, crumbly, decomposed wood. This term is actually a misnomer, because all wood decay fungi require considerable moisture to flourish and consume wood.

Dry time:
The time that it takes for the liquids to evaporate out of a finish. Drying time varies with temperature, air movement and humidity. Contrast dry time with cure time.

Another form of fungi that can grow on wet clothes, plants, siding and other moist objects. Mold and mildew can cause the wood to remain moist, and may lead to early decay if not removed. (See description of mold.)

Mill Glaze:
Starches, resins, sugars and compressed grain left on the wood surface after the planing process. It is caused by the compression and heat generated by machinery during factory finishing processes. Mill glaze reduces penetration of finishes at the wood surface. Always remove mill glaze before applying finishes by sanding, power washing, use of mill glaze removal compounds or other means.

Mold is a term that is used to describe many types of fungal growth. Molds discolor the surface of the wood by turning it different shades of black, green and other light colors. Although mold hyphae can penetrate into the wood, surface discoloration usually can be removed by cleaning, planing or possibly even brushed off. Some molds can develop on the surface of wood below 20% moisture content if relative humidity is high. Mold does not cause structural damage to wood, but is an indication that sufficient moisture is present to possibly support the growth of decay fungi.

The process of restoring pH on wood surfaces back to normal after the use of caustic strippers, chlorine bleach or acids. Neutralization can be done with proper rinsing and/or the use of chemicals.

Oxygen Bleach:
See Percarbonate bleach.

Percarbonate bleach:
is used in wood cleaners to make them safer for use while still having effective cleaning performance. Percarbonate bleach is a more environmentally friendly, safer alternative to chlorine bleach. When properly used, percarbonate bleaches are safer to use around plants and animals.

Sapstain: (also: Blue Stain)
Sapstain is a deep penetrating fungus that causes blue to gray discoloration of sapwood that can penetrate to the heart of the log. Unlike wood rot fungus, sapstain causes no structural decay in wood.

Industry acronym for surface-active agent. Surfactants are used to improve the performance of finishes and cleansers, generally by improving penetration or wetting action. In stains and finishes, they help to create better adhesion to substrate and enable multiple coats.

Transparent Iron Oxide:
A type of tint used in stains and finishes that is ground much finer than conventional pigments. Transparent Iron Oxide pigments allow manufacturers to add higher amounts of tint, while still maintaining transparency. Since tints also act as UV absorbers or reflectors, the result is transparent finishes that last longer and protect better than conventionally tinted finishes.

Ultraviolet Degradation:
Short wavelength UV rays are among the highest energy radiation emitted by the sun. In wood, UV degradation is associated with initial lightening of color, then a deep gray color, finally turning the wood surface to a loose fibrous mass. In finishes, UV causes breakdown of the finish resin that usually manifests itself as some combination of: discoloration, loss of gloss, loss of water repellency and hardening of initially flexible finishes. High quality finishes include UV absorbers and stabilizers to extend their resistance to the negative effects of UV radiation.

White Rot:
In the early stages of decay, the wood tends to turn off-white and can often look bleached. A white stringy residue forms in latter stages of decay, as the strength of the wood degrades slowly.

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