Cedar should not be left to weather

Even though cedar weathers over time to an attractive silver-gray patina that has a certain architectural appeal, research chemists and wood scientists strongly recommend that some form of protective finish be applied to prevent surface degradation.

Weathered surfaces provide a poor substrate for finishes. Even a few weeks of exposure will decrease cedar's ability to hold a finish. Once the finish-wood interface fails, the coating will debond, blister, crack, flake or peel. The longer the period of weathering, the more rapidly the finish may fail.

Artificial weathering of cedar can be accomplished by applying a commercially prepared bleaching stain which is essentially a water-repellent finish containing pigments and other additives. This finish is most effective on textured cedar. To maintain a uniformly gray wood surface, bleaching stain may have to be re-applied periodically.

Natural coloration of newly milled cedar can be retained by applying finishes that contain ultraviolet blockers. Finishes containing both an effective mildewcide and ultraviolet protection are recommended. Since these finishes contain a low percentage of solids, they tend to be high maintenance. Penetrating oil-based stains or light-pigmented natural tones can also be applied to provide uniform color and protect the wood.

Caution: Cedar should not be left unfinished for 6 to 12 months as suggested by some finish manufacturers and others.

(1) Data compiled from research observations. Expected life predictions are for an average location in the continental United States. Expected life will vary in extreme climates or exposures such as desert, seashore, and deep woods, or according to the building's orientation.

(2) Development of mildew on surface indicates need for cleaning and possible refinishing.

(3) Follow manufacturer's recommendations for number of coats.

(4) Expected life of two coats: one primer and one top coat. Applying a second top coat will increase the life of