The Old Forestry Mixture

The old forestry mixture, as some have called it, is a formula for a penetrating oil stain developed by the Forest Products Laboratory in the 1950's. Other than the old forestry mixture, it's more formerly know as the Forest Products Laboratory Natural Finish. The FPL Natural Finish was introduced as follows:

"Many homeowners want a finish that retains a part of the natural color and the grain of new wood or one that enhances the rustic appearance of lumber or plywood. The commercially available natural finishes that form a clear film, such as varnish, have been so short-lived, however, that they are not recommended for exterior use. One durable natural finish is the penetrating stain, developed at the Forest Products Laboratory in the 1950's. The FPL natural finish was formulated to overcome the more serious shortcomings inherent in such finishes of t the film-forming type that are so susceptible to failure by cracking ind peeling. Because the stain penetrates the wood surface and does not form a coating, there is no failure by blistering and peeling even in excessive moisture conditions. There is no coating to scrape before refinishing. Thus, the penetrating stain is easily maintained at a low cost on a variety of wood surfaces. Test results indicate that the first application of the FPL natural finish to smoothly planed surfaces fully exposed to the weather should last I about 3 years. When refinished after weathering, the finish will last much longer. Two coats of stain applied to rough-sawn or weathered surfaces may last 10 years or more."

The exact recipe and full document are listed here. It contains a blend of linseed oil, paraffin wax, solvent, and some other ingredients, including Penta, which is no longer available to the public and restricted to things like the manufacturing of telephone poles and railroad ties. While some of the ingredients are difficult to obtain and Penta is nye impossible, there is at least one alternative on the market. As a ready-made option, a formula similar to that old mixture is available under the brand Organiclear WR-5.

WR-5 Log Home Stain is a superior exterior wood treatment that restores, preserves and enhances the natural beauty of your new or existing log home, deck, fences, railings, shakes and shingles, and outdoor wood furniture. WR-5 offers a unique blend of deep-penetrating premium oils, resins and waxes to create a long-lasting MOISTURE-GUARD™ barrier against harsh weather. To enhance wood life further, WR-5 provides maximum protection against ultraviolet (UV) radiation damage by combining sun blockers to absorb and control UV degradation, thus minimizing wood deterioration. WR-5 penetrating coating will also help prevent wood from cracking or peeling. WR-5 also works very well in high humidity areas. WR-5 allows wood to "breathe" naturally through a micro porous film and prevents moisture penetration. Water beads up and rolls off the exterior wood surface. WR-5 brings out the natural grain beauty of the wood while preventing the wood from cracking and peeling. WR-5 is the perfect choice for the full realm of wood protection your home needs to stand the test of time. For new, unfinished decks, apply two coats of WR-5 this year and then either a third in the Fall or one more next year. WR-5 Clear can be used as a second (if only putting on two coats), third coat, or as future maintenance coats though it won't last as long as a pigmented coat. Some people like to use the clear in this way to "lock" in a particular light color. Made in the USA.