All Natural Homemade Exterior Wood Preservatives

Linseed Oil

• Linseed oil has been used as a traditional wood preservative in Scandinavia for thousands of years. You can make 1 liter of preservative by mixing 17-1/2 ounces of raw linseed oil with an equal amount of gum turpentine. Add 3-1/2 to 10-1/2 ounces of pine tar, depending on how dark you want the finish to look, and 3-1/2 to 7 ounces of isopropyl alcohol. Mix the ingredients well. Warming the preservative, before applying it, will ensure a deeper penetration. Wood treated in this manner will need to be retreated in five to seven years.

Pine Tar

• Pine tar is a liquid that’s distilled from the wood of different trees in the Pinaceae family. Churches treated with pine tar in Sweden almost 1,000 years ago still require little maintenance. Wooden boat builders have also used pine tar for hundreds of years. Thinning pine tar with linseed oil allows it to penetrate faster and ensures that it isn’t as sticky. For the best results, apply it warm. To make a pine tar wood preservative, combine equal parts of linseed oil and pine tar. Heat the solution to 80 degrees Fahrenheit and mix it well.

Borates

• Borates are naturally occurring minerals that are available in several forms, including the common household cleaner, borax. However, while borax will kill insects, a borate powder, such as disodium octaborate tetrahydrate, makes a better wood preservative because it’s more concentrated. To make a wood preservative from borates, add 1 pound of borate powder to a gallon of water. Apply a second coat within 24 hours of the first coat for the best results. Borates will leach out of the wood when exposed to water, so it’s best to apply a synthetic resin water repellent to the lumber after the wood is treated.

Essential Oils

• Some natural plant extracts, such as thyme and geranium Egyptian oils, have been shown to be effective wood preservatives. Ingredients in thyme oil, such as geraniol, thymol and carvone, kill molds and fungi on wood treated by dipping it in the oil.