Dealing With Dried-Out Wood

One of the more common characteristics found on Arts & Crafts homes is unpainted wood. Whether it be cedar trim, cypress rafter tails or an oak, mahogany or chestnut door, natural wood suffers more than its painted counterparts from exposure to the sun, snow and rain.

And, for that reason, most exterior wood is painted, for paint offers more protection. The price we pay, of course, is the loss of the natural appearance of the wood.

Many of these exterior woods were originally left not only unpainted, but unfinished in the belief that their natural oils would protect the wood against the elements. This may have worked for a while, but eventually those natural oils both wear away and evaporate, leaving the pores vulnerable to moisture.

And that moisture eventually turns destructive, either by causing the wood to crack after going through periods of swelling and shrinkage or to develop rot and insect damage if the wood is unable to dry quickly.

It falls to us, then, to protect the natural wood by sealing the pores and preventing moisture from entering.

But with what?

Clear finishes fall into a variety of categories, starting with interior versus exterior. Interior finishes do not have any ultra-violet ray inhibitors, so they break down quickly. They will make the wood look good for a few months, but that’s about all.

Exterior clear finishes have two categories of their own: surface-building urethanes and penetrating oils. Surface-building finishes, also called spar varnishes and similar names, are applied with a brush and dry on top of the wood. Penetrating oil finishes, such as teak oil, can be applied with either a brush or a rag, but any oil not absorbed into the pores of the wood is wiped off five to ten minutes after application.

Each has their advantages and disadvantages.

Surface-building finishes provide more protection coat-for-coat than penetrating finishes, but eventually they do break down. When that happens they flake and peel, which requires a complete sanding or stripping to refinish the wood.

Penetrating finishes may not last as long, but when they begin to wear out they do not peel or flake. You can replenish them simply by applying more oil.

So, which should you use?

If you want a more glossy appearance, opt for a surface-building finish. You can avoid a complete refinishing later if you are diligent about doing a light sanding and applying additional coats before the previous coat begins to flake and peel.

If you want a more natural appearance, opt for a penetrating oil finish. Be prepared, however, to apply additional coats every six to twelve months, depending on how much exposure it has to the sun, in order to provide the wood with the necessary protection.

Either method will work, so long as you don't wait too long to apply additional coats of protection.

Good Luck!

Bruce Johnson

Next Week: Are those flying ants -- or termites?