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often preferred for siding, decks and other outdoor structures because of their beauty, stability and durability, will, if left natural or poorly maintained, begin to show their age. Retailers should have ready answers for customers anxious to restore woods discolored by sunlight, moisture, temperature. microorganisms. dirt or soot.

EXTRACTIVE bleeding can cause discoloration in cedar and redwood. Fortunately, a variety of brighteners are available for treatment.

The first step toward suggesting a remedy is identifying the source of discoloration. The wood may have turned driftwood gray due to ultraviolet radiation and precipitation, or nearly black as a result of mildew growth, soot accumulation, extractive staining, or iron in fasteners, contaminated finishes or airbome particles.

Mildew is often the culprit on decks and siding in moist environments. often in areas with restricted air flow, high humidity or too much shade. While unsightly, mildew is a superficial fungus growth that does not degrade the wood's structure. It commonly appears as numerous small dark spots on the wood's surface with gray, fan-shaped areas spreading below as spores from the original colony multiply and are washed down the surface.

Mildew can be treated with specialty cleaners or common household bleach, later rinsing off mild cases or scrubbing off more severe infestations with a stiff bristle brush and a solution of one cup of trisodium phosphate (TSP), one cup of liquid bleach and one gallon of water.

Naturally occurring chemical extractives in cedar and redwood contribute to their beauty, stability and durability; but sometimes migrate to the wood's surface. High concentrations cause discoloration, which may appear in several forms: boards, high in extractive content, that turn very dark if unprotected by finishes and exposed to moisture; extractives bleeding through paint if stain-blocking oil or alkyd primers weren't used; condensation on the unprimed back side of boards.

A warm water detergent solution that includes a specialty brightener or oxalic acid can be used to diagnose and remove extractive stains. If extractives have bled through paint or stain and aren't readily removed by the solution, the surface may have to be repainted, using a stain-blocking primer.

Tannins may also react to iron and water to form a dark, blue-black iron tannate precipitate. Long-term iron exposure can cause deterioration which appears similar to charring or decay. Iron stains may be easy to detect since they are often near nail heads, screw heads or other hardware.

Scattered discrete, dark flecks may result from the use of steel wool or wire brushes, or from airborne iron dust from machinery, occurring almost immediately after the ironcontaminated wood becomes wet. Rough or surfaced green wood sometimes has inky black marks where it has come in contact with forklift blades, rollers, strapping or other iron materials. Iron-contaminated finishes or water may result in a more uniformly distributed, gray-to-black discoloration.

Most iron stains can be removed by using the same solutions as for removing extractive stains. It may be more difficult, however, to remove and prevent recurrence of nail stains, since they penetrate deeply. The nails should be replaced or countersunk, the holes swabbed with a water repellent and filled with a durable exterior wood filler.

Lime found in mortar and concrete mixes can cause severe stains when spilled or tracked onto redwood. Unfortunately, sanding or bleaching will not remove these black stains.

Many commercial products are available for removing discolorations and restoring the new appearance of cedar and redwood. These products are offered in powder or liquid concentrate form and are typically based upon non-chlorine bleaches, detergents and/or oxalic acid. Selling points are: they are intended for a specific use, come with detailed instructions and are quite effective.

Story at a Glance

First step is identifying cause of discoloration sell cleaners, brighteners and finishes to avoid future problems.

Powerwashing is a popular application method, saving time and labor, but is a choice better suited for experienced contractors. Water and pressure are fundamental enemies of wood, so improper powerwashing can do more harm than good.

And make sure once the wood has been cleaned and restored, a protective finish is applied. High quality products containing mildewcides, water repellents and ultraviolet protection provide the best performance.

ll I'OISTURE is a notorious enemy IYlof fingerjointed wood products. Yet one manufacturer has found a way to fingerjoint lumber before it's ever dried.

After more than a year of research and development, and a rigorous, months-long testing approval process, Wood Fiber Products, Inc., Lockeford, Ca., has devised a new process to fingerjoint green lumber. Their secret is in the adhesive. "I don't know of anybody else that's doing this," explains WFP's Bob Prouty. "No one else could find a glue that would hold. The problem with fingerjointing is when you get the lumber wet, it will reject the glue. The moisture is absorbed, and the lumber might fall apart."

Last year, Wood Fiber Products began working with a glue manufacturer familiar with adhesives which use fiber as a filler. Their unique new adhesive allows WFP to fingerjoint both green and dry without end shrinkage. The joint reportedly is as strong as the wood itself.

He says the process is user friendly and environmentally friendly, devoid of any carcinogens, contaminants, pollutants or other toxic emissions.

The testing on green lumber also provided the company with horizontal structural approval for finge{ointing kiln dried lumber.

WFP plans to fingerjoint both green and kiln dried blocks in redwood, hem-fir and Douglas fir. New products include redwood decking, fascia, siding and fencing products green or dry to specified lengths, hem-fir and Douglas fir dry plate and treated stock to specified lengths with approved grade stamps. WFP is even working with the same manufacturer to develop stains to go with the redwood decking.

The company also produces fingerjoint blanks and studs, edge-glued products, box shook and cut stock.

Prouty attributes the need for such new engineered wood products to the curtailment of federal government timber sales. "New processes such as fingerjointing green lumber will provide yet another way to increase the utilization of what timber that is available," he says.