Cedar enjoys a well-deserved reputation as a wood that takes and holds a range of finishes for extended periods. Nevertheless, the normal life of a finish will be shortened by degradation and discoloration. The causes of degradation are many and have been discussed in the preceding pages.

The causes of discoloration, though not in themselves a failure of the finish, often requires remedial treatment.

Dirt
Dirt is the most benign cause of discoloration and not usually a problem. A periodic cleaning with a mild detergent solution will usually restore the surface finish.

Mildew
Mildew applies both to the fungus and to its staining effects on both the finish and the wood. Mildew is a common cause of discoloration of paint, solid-color stains and natural finishes. Restaining does not solve a mildew problem. When it is time to refinish, clean off the mildew with a commercial mildew-remover then refinish with a coating that contains an effective mildewcide.

Extractives Bleed
Extractives bleed that discolor the finish is usually caused by moisture. To stop stains caused by extractives bleed, moisture problems must be eliminated. Mild staining is often washed away by rain over a period of weeks. In sheltered areas of the building where the stain persists, it may become darker with age and more difficult to remove. If washing with a mild detergent solution does not work, a commercial cleaner may help.

Iron Stains
Iron stains may appear in two forms: the reddish brown discoloration caused by rust, and blue-black discoloration caused by the reaction of iron from nails and other metal objects with extractives from the cedar. To prevent these stains, use only hot-dipped galvanized, aluminum or stainless steel nails when fastening cedar.

Water Stains
Water stains often occur in combination with extractive bleed and mildew growth. These stains can be difficult to remove. Scrubbing the wood with an oxalic acid solution is sometimes effective.

Caution: Handle oxalic acid solution with care as it can be harmful.

Chalking
Chalking is a property of the paint, not the cedar. It occurs when a paint film weathers or deteriorates, releasing pigment particles that act like a fine powder on the paint surface. Chalking is a common cause of fading of tinted or colored paints.

A transparent stain reveals cedar's natural coloration while slowing the color-change process over time.

White-painted trimboards, bargeboards and columns soften the effect of deep shadow lines cast on the siding by wide overhangs and porches.