Asphalt sealing. (Bob Kast / illustration)
(Bob Kast / illustration)

Dear James: Our blacktop driveway is starting to look worn after only three years.

What type of sealer holds up best, and what is the best way to apply it?

— Jay A.

Dear Jay: It is not surprising it looks a bit worn in spots. You should have actually sealed the asphalt driveway within six months after it was laid. Even though it looked very good new, it still needed that initial coat of sealer to keep water from getting into it.

Do some background reading on asphalt to really understand the need and the timing of resealing a blacktop driveway.

A blacktop driveway is a mixture of asphalt cement, sand and gravel. The sand and gravel provide the strength and durability and the black asphalt is the glue that holds them together.

Asphalt is a fairly flexible material initially, and it is attacked by the ultraviolet rays of the sun, air, oil and gasoline drips, etc. These culprits slowly oxidize it and rob it of its oils. This causes it to become brittle and it may even crack.

For about the first three to six months after an asphalt driveway is first installed, it must release very light oils so that it sets up and solidifies. After this initial time period, it needs to be sealed for protection.

First, you will have to decide what type of sealer you want to use on it. The lowest-cost sealers are just basically more liquid asphalt cement. These are easy to apply but will last only about two to three years. If you have a leaky old car, this is definitely not a good choice.

The next best type of sealer contains additional chemicals such as coal tars. These sealers are resistant to oil and gasoline and the ultraviolet rays from the sun.

These also often contain sand and clay particles. The sand improves durability and tire traction, and the clay makes it easier to apply.

The best sealer to use is an acrylic-based synthetic material. This type of sealer is often used on asphalt tennis courts, and it actually has the best appearance. It costs about twice as much as traditional asphalt sealers, but it can last up to eight years. This makes it a better buy in the long run.

Sealing a driveway requires similar preparation to painting your house. Thorough cleaning is essential for good protection.

Two organizations have excellent literature on the treating of asphalt driveways: National Asphalt Pavement Association and the Asphalt Institute.

Wash the entire driveway surface to remove all mud, leaves, loose sand and gravel, etc. This is an excellent application for a pressure washer, but a regular hose and large broom are adequate. A small screw-on “jet” hose attachment will increase the water force.

To clean oily spots, you can usually find special cleaners at an auto supply outlet or outlets that sell the sealer.

Scrape the area first because the oil probably made the asphalt gooey. For badly deteriorated spots, apply a special oil primer over the spot first.

Patch any deep depressions or holes with a cold blacktop patch compound. Any deep cracks should be filled with sand up to a ½-inch from the surface.

Shallow indentations can be filled with soft smooth patching compound. You apply just like icing a cake. These compounds may need several days to dry.

Dampen the cleaned driveway so that the sealer adheres better. Use a broom to remove any puddles. Using a spreader, apply the sealer per the manufacturer’s instructions. Putting it on thicker than is recommended will not help much and will require a lot more sealer.

James Dulley is a mechanical engineer, an avid Do-It-Yourselfer and a nationally syndicated columnist with Email your questions to him at Here’s How. The opinions expressed are his own.