Penetrating finishes preservatives

Weather affects the performance of wood finishes adversely. Both types of finish the film-forming (paints, varnishes) and the penetrating (stains, preservatives) are adversely affected by a combination of the following factors ... 

Penetrating finishes such as stains and water-repellent preservatives ( 7,8) leave little or no continuous coating on wood surface. Because there is no coating, there is no failure by blistering or peeling. These finishes are ideally suited for rough-textured surfaces difficult to paint effectively. 

The oil-base, semi-transparent, penetrating finishes are generally comprised of a resin, a solvent, a UV-absorbing pigment, a wax, and a preservative (7). 

Two basic types of finishes (or treatments) are used to protect wood surfaces during outdoor weathering those that form a film, layer, or coating on the wood surface, and those that penetrate the wood surface to leave no distinct layer or coating. Film-forming materials include paints of all description, varnishes, lacquers, and also overlays bonded to the wood surface. Penetrating finishes include preservatives, water repellents, pigmented semitransparent stains, and chemical treatments. 

Penetrating Finishes. Penetrating finishes, which do not form a film over the wood, include oils, water repellents, stains, preservatives, and surface treatments. 

Penetrating finishes such as stains and water-repellent preservatives leave little or no continuous coating on wood... 

Creosote from coal tar is the most widely used wood preservative for several reasons (1) it is highly toxic to wood-destroying organisms (2) it has a high degree of permanence due to its relative insolubility in water and its low volatility (3) it is easily applied, with deep penetration easily obtained and (4) it is relatively cheap and widely available. For general outdoor service in structural timbers, poles, posts, piling, and mine props, and for marine uses, coal-tar creosote is the best and most important preservative. Because of its odor, dark color, and the fact that creosote-treated wood usually cannot be painted, creosote is unsuitable for finished lumber and for interior use. 

The main purpose on the surface while drying is an eradication of hyphae, already penetrated into the substrate, and superficial left overs from the mechanical cleaning. After complete drying, a penetrating primer can be applied if necessary, then the surface should be finished with a hydrophobic renovating paint containing a carefully chosen film preservative. 

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