Exterior Stains

Unlike paint, which coats the surface, stains penetrate and allow the natural texture of the substrate (surface being stained) to show through. Whether you choose to accent the grain with a semi-transparent stain or mask the grain with an opaque stain, all stains provide some measure of substrate protection. This protective quality is highly important for exterior applications. Exterior stains are primarily used on wood siding and shingles, decks, outdoor structures and furniture. Before you learn about all of your available options, use these questions to start thinking about what your project needs are:

• Are you applying stain to a previously stained or painted surface?
• Do you want the grain and natural color of the wood to show through the stain?
• Are you interested in a color that is not a wood tone, such as blue or green?
• Is lasting performance or external appearance your primary concern?
• Does the surface need to be stripped, sanded or cleaned?
  
  

Quality, Type, Life and Surface Preparation

It’s always important to buy high-quality stains or paints to protect substrates, but it’s especially important when it comes to exterior projects. Exterior surfaces and furniture are subjected to harsh conditions day in and day out, from moisture and wind to direct sunlight and fluctuating temperatures. A good stain will last longer, saving you money and time spent on refinishing, so be sure to think about long-term benefits in addition to initial cost.

Water-Based vs. Oil-Based: Like paints, stains are available in oil-based and water-based formulas. Water-based stains offer better adhesion to surfaces that have been previously painted or stained with oil-based stain. Water-based stains are also recommended for woods that have a natural resistance to rotting, such as cedar, redwood and cypress. Oil-based stains are generally recommended for decks and other areas exposed to particularly harsh conditions. There are some newer latex/oil stains that offer benefits of both oil- and water-based stains.

• Water-based stains are breathable, so they won’t trap moisture
• Oil-based stains offer better penetration and durability
• Some manufacturers offer hybrid stains

Stain Base	Major Advantages
Oil-based(alkyd)	Better penetration Excellent durability Longer drying time allows more time to achieve an even finish Special deck stains deliver maximum durability for harsh conditions
Water-based(latex; acrylic)	Better color retention Less odor Breathable Nonflammable Soap and water cleanup Quicker drying

Opacity and Color: Opacity determines the amount of visible wood grain on the surface. A finish with low opacity will have less pigmentation, resulting in a natural wood grain appearance. If you select a stain with a high level of opacity, there will be more pigmentation, resulting in the wood grain being covered or masked. Color is closely related to opacity. Lower opacity levels will allow the wood's natural color to show through. Higher opacity levels will mask the wood color with the stain's pigment, achieving a painted look without losing the texture of the wood.

• Stains are available in a variety of colors, including blues, greens, reds and yellows
• Opaque stains last the longest but hide the grain and the color of the wood

Opacity	What You Should Know
Semi-Solid Stains	Designed to almost completely hide the natural wood grain and color Penetrates, stains, seals and protects, while providing a durable finish Longer life than semi-transparent stains due to increased UV blockage
Semi-Transparent Stains	Provide a transparent protective layer and allow the grain pattern to show Can be applied over bare wood or previously semi-transparent stained wood (if it has not been sealed)
Solid (Opaque) Stains	Provide a stained finish which hides grain pattern Can be applied over previously painted surfaces Longer life than semi-solid stains

Life: Life is how long the finish or stain lasts. Once again, opacity is an important factor in determining the longevity of a stain product. A stain with a low opacity level contains less pigment and will generally have a shorter life. The more pigments present in the stain/finish, the longer the product life will be. Stain life is reduced on surfaces that are highly trafficked or exposed to harsh conditions.

• Opacity increases the expected life of the stain by blocking more UV rays
• Though some stains cover in one coat, applying two or more coats increases the life
  
  

Surface Preparation: Make sure you take the time to prepare the surface prior to staining. If you don’t, you’ll end up wasting more time in the long run because even the best stains won’t last if the surface isn’t prepared correctly. If the surface has been painted or sealed previously, the paint or seal should be removed. Once bare, the surface needs to be clean, dry and free of mildew, dust and loose wood fibers.

• Prior to staining, make sure the surface is clean and free of loose wood fibers
• If bare wood is gray or weathered, it should be sanded down
  
  

Features

Gel Stains: Oil-based gel stains resist drips and won’t raise the grain of wood. Because gel stains don’t penetrate deeply, they offer more control but tend to require more coats to achieve the desired color.

Mildew Resistance: Water-based stains are all mildew-resistant. Oil-based stains, on the other hand, can encourage mildew growth, so look for ones that specifically say they are mildew-resistant if you’re going with oil.

Safety: Water-based stains are safer for people because they don’t produce harmful fumes and they’re not flammable. They are also more environmentally friendly. Oil-based stains contain more VOCs (Volatile Organic Compounds), which cause air pollution. Oil-based stains and the rags used with them require special disposal to prevent fire and pollution.