If you Google, you will find home-brew ways to treat wood, but from what I recall the methods are slow, messy, and most likely toxic. To refinish, a thorough cleaning of the wood with a stiff bristle brush is usually adequate before applying the water-repellent sealer or penetrating stain finish. Since high-grade resistant materials are difficult to obtain in structural sizes, the less durable species of wood are often used. Take as much time as you need to perfect the treatment of unfinished wood furniture. Sand the wood down if the the vinegar and baking soda and enzymatic cleaner methods fail to yield results. For use in less critical areas such as landscape timbers, corrosion resistant fastenings may not be necessary.
Since water is used as a carrier for the chemicals, the wood should be redried after treatment to a moisture content of 19% or less unless otherwise specified. I’m all for scrounging and using ‘free’ stuff, but you also have to use the correct materials and methods for the task at hand. To get the best finish possible make sure you fill any dents or cracks in your door with a good quality wood filler and sand it smooth, and then give the door a coat of undercoat before applying your chosen paint.
Any added cost due to having wood treated or buying treated wood is relatively small when compared to total building expenses and life-time benefits. Around mid-missouri and Lawrence, KS I see a lot of triple 2x wood girders for support beams – most are non-treated lumber. This bridge made from acetylated wood near Sneek , the Netherlands , is designed to carry heavy traffic.
If you’re looking to retain the natural untreated or freshly sanded look which is lighter, consider Osmo Polyx Oil Raw 3044 or Fiddes Hard Wax Oil Natural. But in the old days my uncle used to soak ground wood in used oil from oil changes with a little diesel mixed with it but it was temporary at best. As a result, wide ranges of service life in the lumber of even a highly durable wood may be experienced and rapid decay is occasionally reported. The easiest and quickest solution is to leave your doors untreated without applying any coating.
Oh another thing is, if you use T&G, longer is not necessarily better… It is usually cheaper per linear foot if you get longer ones (ex 16′ vs 12′) but it is such a hug pain to tab a long not-perfectly-straight board together… That 2′ and 4′ make a huge difference as to how easy it is to handle. Studies conducted at the University of Kentucky on gluing treated lumber showed that lumber treated with a water-borne preservative would be a satisfactory choice for glued frames, such as those shown in the Kentucky greenhouse plans. Brown says that if you already have the older, arsenic-treated wood in your garden, don’t panic.
The degree of success in using treated wood depends not only on the preservative and wood species but on the treatment method as well. Over 70 years ago, Dr. Karl Wolman invented the process of infusing preservative deeply into wood products. Now the floor has been prepared, it must be sealed with either a wood floor lacquer or wood floor oil The choice of oil or lacquer (sometimes known as varnish), is completely your choice. Wood destroying organisms need three things for survival: water, food (cellulose from wood) and oxygen. Copper naphthenate formulations are available from home centers, lumber dealers and hardware stores.
Another helpful tool to identify wood treated in accordance with AWPA Standard U1 is the Check Mark” program developed by the Western Wood Preservers Institute. One restoration company uses an interesting historical technique to clean old plank floors. Any film-forming finish is likewise subjected to excessive stress because of the continuous shrinking and swelling of the wood that results from changes in its moisture content. In the end, the industry agreed to voluntarily eliminate use of CCA for residential use.
AWPA’s Standards are universally specified for wood preservation in the US, and are recognized worldwide. Grease treatments are also used as remedial measures when untreated wood is placed in areas of high decay hazard. These methods are the only means by which the purchaser of small amounts of treated wood can be assured of proper treatment. Depending upon the solvent used, penta treated wood will vary from light to dark brown in color. Table 4 shows the effect of pressure treatment compared with soak, dip, and untreated methods using penta. We recycle untreated wood with ease but treated wood isn’t so easy to repurpose.