How to clear up deck finishing misconceptions

fiVER one quarter of all homes in \-Ithe U.S. alreadv have wood decks. Builders are incieasingly making decks standard features of new homes and owners of older homes often add decks for outdoor enjoyment and to improve the value of their property.

This trend has spawned an avalanche of new products for cleaning, sealing and protecting outdoor wood. And with the abundance of options on store shelves comes uncertainty about which products and techniques are best for deck finishing and maintenance projects.

Salespeople should be able to alleviate confusion by having ready answers to the most common misconceptions about finishing, restoring and maintaining wood decks, according to Wolman Wood Care Products.

Mir"oo""ption No. 1: Pressure treated lumber, cedar and redwood are maintenance-free.

Everyone knows that cedar and redwood are naturally durable, and pressure treated wood often comes with a lifetime warranty against rot and decay. Years ago, cedar and redwood came mainly from old growth trees with high levels of resins that were naturally resistant to decay and insects. Much of the cedar and redwood used in deck construction today is from younger, second growth trees, and these trees are less resistant to biological enemies. In addition, all redwood and cedar - old or new growth - may be susceptible to damage from rain, snow and sunlight.

As for pressure treated wood, its warranty covers decay and insect attack, but pressure treatment does not protect against weathering cycles of wetting and drying. The elements can cause wood to check, crack and splinter over time. What's more, ultraviolet rays from the sun can destroy the top layer of wood cells, resulting in a gray, bleached appearance.

No wood is so naturally resistant as to be maintenance-free. Protective finishes, such as water repellents and preservatives, are the best way to help avoid water and sunlight damage.

Mir"oo"uption No. 2: A coat of stain or water repellent will make gray wood look bener.

Just as you would not wax your car without washing it first, you should not apply a finish to a weathered deck without properly preparing the surface. Stains, mildew and algae must be removed, otherwise they'll be sealed in with the new finish. And, most important, cleaning helps prepare the wood so that the finish penetrates deeply and bonds to it properly. Washing the deck with water alone will not do the trick. Water may remove some debris, but won't get rid of ground-in dirt, mildew and algae. Nor will it remove the top layer of gray, sun-damaged wood fibers, which can interfere with adhesion of newly-applied finishes and result in weakened performance (poorer water repellency, UV resistance, etc.).

The best way to prepare weathered wood for refinishing is to use a commercial wood brightener/restorer/reju-

Story at a Glance

Answers to common questions about finishing decks best products for each job.

venator. Popular wood preparation products come as economical powder concentrates that are mixed with water and sprayed on to the wood surface. The surface is then brushed and rinsed off. Brushing is important and should not be overlooked because it helps remove the top layer of dead wood fibers, which again, could interfere with adhesion and performance of the new finish.

Mir"orr""ption No. 3: Bleach is great for cleaning decks.

Homemade solutions of household bleach and water, and chlorine bleach-based cleaning products, which contain sodium hypochlorite or calcium hypochlorite, are effective against mildew but may harm surrounding plants, shrubs and grass, and do little to remove dirt and sun-damaged wood fibers. After all, if chlorine bleach were effective in removing dirt, you wouldn't have to add detergent to it when washing clothes.

When used on decks. chlorine bleach can do more harm than good. It can leave the deck with a whitish, unnatural tone - a "bleached" look. And recent studies have found that using chlorine bleach-based products results in premature coating failure and graying of the wood.

There are products on the market that do not contain chlorine bleach and are more effective at cleaning weathered decks. A good brightener helps lift and loosen ground-in dirt, mildew and algae, and removes gray, sun-damaged wood. This results in a bright, natural-looking surface that is ready to accept any type of deck finish.

Mir"or,"uption No. 4: New wood should be allowed to weather or "season" for several months before applying any type offinish.

This is an outdated concept. Research shows that letting new wood go unprotected for even a few weeks after installation can cause damage and surface degradation that interferes with adhesion of the finish coat.

New decks should be protected from the elements as soon as possible with water repellent finishes or preservatives that are specifically designed for application to new wood. If the wood is very wet, it should be allowed to dry before finishing (l-2 weeks is usually adequate).

Mir"orr""ption No. 5z Ail clearfinishes are pretty much alike.

There are more deck sealers and finishes on the market today than ever before. In the area of clear finishes there are "water repellents," "water sealers," "clear wood preservatives" and "clear wood finishes," just to name a few. And not all are alikethere are important differences in the type and quality of these clear finishes when it comes to decks.

The terms "water repellent" and "water sealer" are used interchangeably. They refer to products that protect wood from rain. dew and snow. There are "all-purpose" type formulas on the market, designed to go on a variety of surfaces including wood, concrete and brick. A better choice for decks, however, is a water repellent designed specifically for exterior wood. The best formulas for wood decks contain a mildewcide to protect against mildew growth. They also contain long-lasting water repellents. Some products state on the packaging that they meet federal water repellency specification TT-W-5728, p. 3.7. This is the test standard used by the wood window and door industry, and it assures effective protection against moisture damage.

Most water repellents are clear, but some offer hints of color with "toner," providing a semi-transparent sheen that doesn't mask the grain.

"Clear wood finishes" are designed to keep wood looking new. While these finishes are usually transparent after drying, they are not necessarily colorless. They often contain a small amount of pigment and oil to impart a natural tone to the wood and help protect against UV damage. The bestperforming products in this category are "wood finishes and preservatives." In addition to containing Wblockers, these formulas protect against mildew, rot and decay. Products that contain EPA-registered preservatives assure long-lasting protection.

Penetrating semi-transparent stains (stains made specifically for decks), water repellents and clear finishes are better for horizontal surfaces. These products generally do not blister or peel as they age. They may fade over time, but applying a new coat is a simple task. They also contract and expand with the wood during extreme weathering cycles, preventing peeling and cracking.

Mir"orr""ption No. 7: When it comes to finishes, more is better.

Mir"or,""ption

No. 6:

Paints and solid color stains offer the best protection for wood declcs.

Film-forming finishes, such as paints, have been used for centuries to protect wood. For most applications paint is very effective against sunlight and weathering since it forms a physical barrier, blocking out the elements. On horizontal surfaces, however, paints and solid color house stains are not very suitable. Standing water can work its way beneath the film, resulting in blistering and peeling. And in order to recoat, the deck must first be stripped down to the bare wood by sanding.

A common problem with wood finishes is over-application. Many users mistakenly believe that when it comes to applying a finish, more is better. Most deck finishes, however, are designed to penetrate the wood rather than form a film on top of it. Putting on too much leads to a buildup of the finish, forming a film that can ultimately crack, blister or peel. Over-application of water repellents can result in a surface that is waxy and slippery. Over-application of stains or clear finishes can result in a sticky surface, as the buildup interferes with their drying properties.

For most deck finishes, one coat is usually sufficient. In those situations where two coats are needed, it is important to allow the first coat to properly penetrate and dry before reapplication. Always check product label directions for proper coverage information.