Exterior Sealers

Exterior sealers provide excellent protection for decks and wood surfaces, driveways, patios and sidewalks. They seal porous surfaces so that a finish coat can develop a uniform sheen. They also protect the finish coat on masonry from alkalinity and efflorescence (a white crust of salt), and they seal out moisture. Before you learn about all of your available options, consider the following questions and start assessing your project needs:

• What material or materials are you sealing?
• Are you looking for a clear or colored sealer?
• Are fumes and easy cleanup a key consideration?
• Is durability or appearance your primary concern?
  
  

Type, Base, Color, Life and Surface Preparation

Without proper sealing, exterior wood and masonry are quickly destroyed by the harsh weather and traffic they endure. When purchasing sealers, you have a wide array of choices. Some of your options will be determined by your intended applications and others are simply determined by your preference. A high-quality sealer recommended for the specific task you plan to undertake will protect better and save you money on resealing in the future, so make sure you consider the long-term benefits of various sealers in addition to the initial price tag.

Type: The term “sealers” is generally used to include wood repellents, water-repellent preservatives, wood toners and concrete sealers, though naming and features can vary widely by manufacturer. Many sealers are named according to their recommended application. However, the manufacturer often calls out additional uses. For example, a brick and stone sealer may also be appropriate for stucco and cement.

• Wood toners are usually semi-transparent to enhance color without completely hiding the grain
• All-purpose sealers can often be used for wood, cement, masonry and even canvas
• Many concrete sealers are designed to withstand the rigors of traffic, chemicals, road salts and more

Type	What You Should Know
Concrete Sealers	Protect against damaging effects of road salt, acids, household cleaners and weather Resist dust and make surface easy to clean Help control water evaporation Ideal for use under latex, alkyd or polyurethane paints or carpeting
Water Repellents (Water Sealers)	Form protective coating for surfaces, ranging from wood to masonry Provide protection from water damage, stains, wear and more
Water-Repellent Wood Preservatives	Water repellents protect against rot and decay by preventing the growth of mildew, fungus, mold and more May also protect against wood-eating bugs EPA registered
Wood Toners	Water repellents with a tint Provide added protection from UV damage due to tint Can be applied over previously painted surfaces

Base: Like paints and stains, sealers are available in water-based and oil-based variations. Water-based sealers allow moisture to escape, whereas oil-based sealers can trap moisture in the wood, which can cause rot and decay. Water-based sealers also provide natural mildew resistance, while oil-based sealers may feed the growth of mildew if they don’t contain added mildewcides. Oil-based sealers, however, offer better penetration.

• Water-based sealers have fewer volatile organic chemicals, so they are safer for people and the environment
• Oil-based sealers and unclean applicators require special disposal to prevent fire and pollution
• Water-based sealers clean up with soap and water, while oil-based or alkyd require solvents
  
  

Opacity and Color: The more pigments a sealer has, the more opaque it is and the more it will mask the surface. Though clear water repellents may have a slight tint to bring out the natural look of the surface beneath, they have virtually no opacity. Most wood toners are semi-transparent, so they change the color of the wood but don’t hide the grain completely.

• Sealers with more pigments last longer but mask the grain and/or color of the surface
• Sealers are available in an array of wood tones, as well as other colors
  
  

Life: Life is how long the sealer lasts before needing to be reapplied, so a longer life will save you time, effort and money, while keeping the surface better protected and looking great. Sealers with more opacity have a longer life, but sealer life is reduced on surfaces that are highly trafficked or exposed to harsh conditions.

• Sealers with more opacity block more UV rays, so they last longer
• A higher percentage of solids indicates better quality and longer life
  
  

Surface Preparation: Take the time to prepare the surface according to manufacturer instructions, or you’ll end up wasting more time and money resealing in the long run. If the surface has been painted previously, the paint should be removed, though you can spot-seal bare areas on a painted surface. Once bare, the surface needs to be clean, dry and free of mildew, dust and loose wood fibers.

• Prior to sealing, make sure the surface is clean and free of loose wood fibers
• Follow manufacturer instructions for cleaning solutions and techniques
  
  

Features

Paintable Sealer: Using a sealer prior to priming and painting can extend the life of your paint job. Look for a sealer that specifically says that it can be painted; otherwise your primer or paint may not adhere correctly.

Primer/Sealer: Some manufactures offer combination primer/sealer, saving you from applying them separately if both are needed. These products combine the benefits of sealers and primers for better paint performance on porous surfaces.

Sheen: Sealers are available in a variety of finishes from flat to high gloss. A high gloss creates a sleek, wet look, dries hard and tends to protect better from abrasions. Glossier surfaces are also easier to clean but tend to highlight surface imperfections and may be slick when wet.