Expert Tips on Exterior Wood Stains

To understand exterior stains, it's important to recognize that these popular products fall into two broad categories, according to experts at the Paint Quality Institute, a leading authority on the subject. There are "semi-transparent" (sometimes called "transparent") stains, and "solid color" (or "opaque") stains. 

Semi-transparent stains are applied in a relatively thin coating that allows both the grain and texture of the underlying wood to show through. 

Solid color stains contain more pigment than semi-transparent stains, are of heavier consistency, and go on in thicker coats, which still reveal the texture of the wood, but not the grain. Because they are more highly pigmented, these types of stain have more "hiding" ability, which makes them a better choice for blemished wood, and on projects involving different types of wood. 

Both semi-transparent and solid color stains come in oil-based and latex-based formulations. Oil-based exterior stains tend to penetrate wood, while latex stains form a protective film on the surface.

Surface Preparation

Good surface preparation is essential when applying any type of stain. To that end, the wood surface must be free of all dirt, dust and mildew. 

When staining new wood, be sure to sand any shiny areas. The shininess may indicate the presence of mill glaze from the milling process, which can prevent the stain from adhering properly. 

Before staining bare wood that has weathered for more than a few weeks, thoroughly sand the surface to remove loose fibers and provide a fresh, stable surface. This will help the stain adhere to the wood. 

When re-staining wood, carefully power wash the surface with plain water to remove any loose stain, wood fibers, dirt or mildew. Be careful to not mar or gouge the wood with the power washer, nor drive water into the material.

Applying Stain

Because stains have less pigment than paints, and since they are often applied in just a single coat, any mistakes in application procedures can be quite noticeable. So, it's important to apply stains in the right way. 

When staining lap siding, apply the stain horizontally, using either a brush or roller. Start at the top of the wall or surface, applying stain all the way across, a few boards at a time. Then move on to the next lower boards, and continue in this manner, until reaching the bottom. 

In a similar way, when staining vertical sections, such as board-and-batten siding, apply the stain from the top to the bottom of each section before moving on to the adjacent section.

Use a Quality Stain

Unlike paints, which are often applied over a primer and in multiple coats, exterior stains are typically applied directly to unprimed wood in just a single coat. 

With so little coating to protect the wood, the Paint Quality Institute recommends that you use a high quality stain to best withstand the elements and to maintain a good appearance -- for example, a top quality 100% acrylic latex exterior stain. Such a product will provide maximum adhesion to the wood surface, and will resist fading and mildew growth much better than economy products will. 
Even so, keep in mind that because of their relatively thin film, exterior stains have to be reapplied more often than paint. 

For more information on paints and stains, visit the Paint Quality Institute Web site at www.paintquality.com.

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