Stains & Finishes

When using wood in an exterior application, why is it so important to seal the wood?

There are two answers to this question--- SUN & RAIN. The effects of sun and rain are tough on all species of wood. Use of a sealer to combat the premature aging and movement of wood is necessary to guarantee the future beauty of your wood project.

EXPLANATION OF THE SUNS EFFECT ON WOOD:
Excessive heat and UV rays can damage the cellular surface of any exterior wood product. As the sun creates heat, it rapidly draws moisture out of the wood. Some species, due to their cellular make-up, can dry out too quickly if left exposed. This rapid drying can cause dimensional instability problems where the wood tends to warp, twist, crack and split. UV rays can actually bleach out the natural color of the wood. The only way to slow this process is to pick a stain or finish that has a darker pigment. With some species like Redwood, if left un-sealed, you can use an oxalic acid to bring back the natural red color of the wood. The sun can be hard on exterior wood. To protect the natural beauty of your wood, select a high quality exterior stain or finish that has a proven tract record.

EXPLANATION OF MOISTURE AND WOOD
Wood is a natural, porous substance. It absorbs and releases moisture as the seasons change. Wood placed in an exterior application is affected by these changes in the weather. As wood absorbs and releases moisture, it can swell and shrink. Some species of woods, due to their cellular structure, absorb and release moisture more rapidly than other species of wood. If a wood absorbs moisture too rapidly, dimensional instability can occur in the wood. Dimensional instability can be characterized by, swelling, shrinking, twisting, cupping, warping, bowing and cracking. Use of a good exterior stain or finish can retard excessive moisture from penetrating the woods surface.

EXPLANATION OF THE INTERNAL CHARACTERISTICS OF WOOD:
Most wood has a range of equilibrium moisture content of between 8-20%. A particular wood species natural, exposed reaction to moisture and drying can cause aesthetic problems like warping, twisting, splitting, bleaching, etc. Stains and primers protect the bare surface of the wood by absorbing or penetrating the wood’s cells. The variance between low to high percentage of moisture in any exterior wood can be decreased by the use of a good stain or primer. Protected wood looks better and lasts longer. Another natural characteristics of wood is its need to breathe. By understanding this aspect, you can make the best choice in choosing an exterior sealer for your wood.

EXAMPLE: (Why wood needs to breath?)
Many customers have come into our store needing to replace exterior “Painted only” wood that has failed over time. The reason the paint failed is because the bare wood had not been primed before it was painted. Paint is only a coating. (Which will not allow moisture in or out of the wood). Over time as a paint fails, moisture can absorb though exposed areas and then get trapped in the wood. If no primer is used, the wood will not slow the absorption of moisture into the wood and the moisture content remains too high. If woods moisture content stays above 28% for very long time microorganisms can grow in the wood causing rot and decay. Always protect your wood first with a good primer before you paint, or use a stain that naturally absorbs into the wood. Either primer (and then paint) or stain will protect your wood. Also, if you have excessive moisture somewhere around your house, it’s best to find out why and resolve this root issue soon. Excessive moisture close to bare or poorly protected wood (due to over grown shrubs, broken gutters, no gutters or any other source), is terrible for wood because it won’t allow the wood to breath or ever let off enough moisture to guard against rot or decay.

While it is always important to seal your wood at application, selection of a supplier to purchase your exterior wood from can be just as important. Please follow these steps in your selection of a lumber company to buy your exterior wood products.

Check the following things:

1. Never buy wet lumber (Lumber you buy should be kept in a dry storage bin out of the weather.)
2. Always ask if lumber has been dryed below at least a 19% moisture content.(Even Treated lumber)
3. Hand pick your lumber. Remember you will have this wood for a long time. Take the time to select the pieces of wood you want for your project. Educate yourself on the natural characteristics of the wood so you don’t have an unrealistic idea of how any particular species will react to your application.
4. Buy your wood from a supplier that is knowledgeable about the wood they sell, or at least will be willing to take the time to find you answers about the use of a species of wood for a particular application.
5. Buy your wood from a supplier that offers both product and support information on how to best seal your exterior wood products. Sealing your exterior wood product with a high quality exterior stain or finish is just as important as the wood choice.

Stain and Paint Products:

When choosing between using a paint or stain to finish an exterior wood surface, one must first understand the difference between paint and stain products.

STAIN APPLICATION DEFINED: Exterior stains such as Cabots or TWP are excellent for both horizontal surfaces like decks and vertical surfaces like siding and sidewalls. The stain absorbs into the wood’s cells and controls and retards both the quantity and speed at which moisture is absorbed into the wood. These stains and finishes are perfect for both dryed treated woods and natural exterior wood species like Cedar, Redwood, or IPE.

PAINT APPLICATION DEFINED: When you paint an exterior wood surface, you should be concerned about protecting your wood investment. Insist on a high quality exterior wood primer like Cabots Problem Solver Primer ®. A paints value is its ability to hide defects in the wood. Good paints have a hard surface protector along with a mildew resistor. For instance Cabot's "The Finish"® has a heavy Teflon surface protector and it’s 100% acrylic finish resists mildew and dirt pick-up. A hard surface paint like “The Finish”® may be the best choice for both our Incense Cedar and Redwood due to the fact that both these species are much softer woods. Of course, Cabot’s Problem solver Primer® must be used as an under coat to guard against extractive bleeding which is a natural mineral stain that can rise to the surface of the wood through a stain or finish, causing a discoloring affect. For more information: www.cabotstain.com

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