What Are the Differences in Driveway Sealants?

Coal Tar

• Coal tar sealers are made from distilled and refined coal. They’re more durable than asphalt-based sealers, and driveways sealed with them stay black longer than those sealed with asphalt sealers because they include stabilizers that resist ultraviolet rays from the sun. Coal tar sealants also resist water very well. Driveways treated with this type of sealant don’t suffer as much damage from petroleum products like gasoline, oil or brake fluid, which can eat away at asphalt driveways. That’s because gasoline and oil are solvents for asphalt, but not for coal tar. On the other hand, coal tar sealants emit a strong odor and can cause respiratory problems for some people. They can also irritate the skin and cause photosensitivity.

Asphalt

• Asphalt-based sealants are derived from petroleum and can be water-based or based on coal tar. Water-based asphalt sealants don’t emit high levels of polluting chemicals like coat tar sealants do, so they’re better for the environment. For this reason, they also cost more. Asphalt-based sealants also contain polymers and other ingredients that add to the cost. They repel water fairly well and don’t give off strong odors or cause photosensitivity. However, they aren’t as good as coal tar sealants when it comes to resisting ultraviolet rays, and driveways sealed with this kind of sealer are apt to develop stains from spilled motor oil or gasoline

Quality

• Another way to compare sealants is by comparing the amount of solids in the formula. Driveway sealants contain water, sand, clay, other fillers, various chemicals and the binder, which is either the asphalt or the coal tar. Formulas that contain a lot of solids are better quality and will do a better job sealing your driveway than formulas that don’t contain as many solids. Since formulas are proprietary, it’s hard to compare them, but one rule-of-thumb is to look at a company’s warranty. The best sealants will give you a five- or six-year warranty. Plain sealers will only offer one to three years. High quality sealants are also easy-stir or no-stir.

Concrete

• Several types of sealants are available for concrete driveways. Acrylic sealers are often mixed with epoxies, silicones or polyurethanes to make them more durable or water-resistant. Performance varies depending on their form, but the best acrylic is a pure acrylic resin. Epoxy or polyurethane sealers are also available but they cost more than acrylics and can be more slippery. Moisture problems can occur with epoxies and polyurethane sealers. Silicone sealers penetrate concrete and form a chemical barrier to water and oil.