Applying wood preservatives to your outdoor wood items is often necessary in order to get the most out of your furniture, patios and decks. While a number of people would like to use some of the more enduring woods on their outdoor projects, their cost keeps it a dream. Cypress, redwood and cedar are the most common weather resistant woods in use in this country. There are some areas of the United States where these woods will last for up to a century. Unfortunately, in the South, even the hardiest types of wood will not last as long as you might think.
Cypress is the most common durable wood in our area of the country. Big bald cypress forests used to be located all over the United States. One of the largest cypress forests once stood where Philadelphia, Pa., is now located. Cypress species, of which cedar is one, are still found everywhere. Cedar and western cedar are very pleasant woods to work with. Most cypress woods are easily worked.
Black locust, a member of the Legume family, is another wood that is very long-lasting and is used for fence posts in many locations. The early colonists in New England used locust for corner posts on their homes.
Most of us can afford moderately priced woods. The most durable of these is pressure-treated lumber. The big advantage to using pressure-treated wood is that the chemicals that are used to preserve the wood fiber have been forced, under pressure, into the very cells of the wood. This lumber will last on the average of about 20 years in a humid climate like the South and southeast. Pressure treated lumber needs to weather for about six months before you can paint it with any success.
Now for preservatives. Chemicals that are “user applied” can only be brushed, daubed, rolled, mopped or sprayed onto the surface of the lumber that you want to treat. This application will only penetrate the very outer layer of wood. Even spraying or soaking does little to help the chemical infiltrate more than the outer layer. Wood preserving chemicals do enable wood products, used out of doors, to last from four to seven years and sometimes longer. These chemicals need to be reapplied for continued protection.
As a rule, wood preservatives should be applied to bare wood. If the wood has been sealed or primed with some other materials the preservative will not enter the wood. This is not to say that most preservatives cannot be painted over with some other coating or color. The most common chemicals used for preserving wood are: linseed oil, stains, oil, creosote, asphalt roofing compound, copper-8-quinolinolate, water-repellent, copper naphthenate, paints and varnish.
Linseed oil is very often the carrier or base for many oil-based paints. You should use boiled linseed oil. It can be applied with a brush. Let it soak in for a few hours and then apply a second coat. Let the second coat dry for an hour and then wipe off any excess. Linseed oil does nothing to hide any defect in wood. If the wood you used is less than desirable you may want to hide the surface. If this is the case, don’t use linseed oil. Linseed oil will highlight a wood’s grain. In the past it was used in conjunction with waxes for hand rubbed finishes on furniture.
Stains are probably one of the best choices. Penetrating stains come in two categories, pigmented and semitransparent. Pigmented stains hide flaws and semitransparent highlight the wood grain. Stains come in a variety of colors. They can be applied by brush, sponge pad brush, roller or paint pad. If possible, when using a stain, take a scrap piece of wood (the same wood that you will use it on) and test how the stain will go on the wood.
Old motor oil was once used to coat the bottom sections of fence posts before they were put in the ground. The oil would soak into the wood and help to keep moisture out. Occasionally a bit more oil was poured around the bottom of the fence post where it meets the ground. A friend of mine told me of an old fellow that drilled all his fence posts from the top to the bottom and then would fill this column with old oil and then cap the hole. The oil would wick out through the wood preserving it. These posts had lasted over 40 years by doing this. Of course he would check the oil in his posts every once in a while.
Creosote is a very good preservative for lumber that will be on the ground or in the ground. Two or three coats is recommended with a drying period of a day or two between coats. Using creosote will extend the life of lumber eight to 10 years in our climate. Creosote may be banned in your area. You will need to check local codes. I’m thick skinned, and I find creosote can burn if you get some on you. It’s hard to get off once it is on. Don’t use this material where people can touch it.