OneTime is a very unique product in this category, in that it isn’t oil or water based. Instead, this is an acrylic resin product which is UV cured. When applied, the resin actually soaks into the wood, bonding with the wood fibers. There is no outgassing while drying and no VOCs, which should make the EPA happy. However, the curing process takes a full two days of sunshine to accomplish; so be sure to check the weather before using it. The product can be used on new or old wood, the only requirement is that previous paint and stain be removed. While the product’s color will fade with time, the protection for the wood is guaranteed to last a full seven years.
Thompson’s is a personal favorite of mine, which I have had very good results in using. This is an oil based product, which soaks into the wood providing what the manufacturer calls “three way protection.” It waterproofs the wood, so it won’t be affected by the moisture; protects the wood against rot and mildew; and has a UV absorber to retard fading from sunlight. I might add to that the protection it offers against the wood drying out and cracking. Thompson’s comes in various colors and can be applied to any wood, even if it has previously been painted, stained or is weathered. Oil based stains and paints can be used over it.
Olympic is another oil-based product, which soaks into the wood much like Thompson’s does. Although they offer tinted versions, this clear contains advanced UV inhibitors, which actually work better than the tinted versions. It also protects against mold, mildew and algae. It also has a “scuffguard formulation” which protects the wood from discoloration caused by scuffing and scraping. The product is guaranteed to protect water damage and graying for a minimum of two years on decks and three years on fences and siding. It is 100 percent VOC compliant.
Preserva-Wood is a unique product in that it is intended for use in restoring weathered wood and not just preserving it (which it does also). This is a totally organic formula, which uses no acids, corrosives or bleach. The unique blend of resin and oil penetrates wood cell structure, restoring the cells and restoring the surface of the wood. Once treated wood returns to looking new again. Since it penetrates the cells, it doesn’t leave anything on the surface to peel or chip. The finish resists, mold, mildew and algae, as well as splitting and warping.
This is a different sort of wood preservative, primarily intended to protect wood from termites and other wood eating insects. It gives the wood the green tint of being pressure treated, although that isn’t what it is doing. The green color comes from the copper oxide that is in the product. AT the same time, it protects the wood from rot and decay, like other wood preserving products do. This product is most effective when applied to wood before it is put in the ground.