Need to remove sap from asphalt?
Q Our walkway is asphalt, and we sealed it about three years ago with the standard sealing material. This autumn, sap from a nearby pine tree dripped onto the walkway, leaving many white spots. How can we remove the spots without damaging the surface? We have tried using mineral spirits, with no success. Is there a product that can remove the dried sap?
A The alcohol-based hand sanitizer that you may have stocked up on, works wonders for removing pine pitch from almost any surface, and it won't hurt asphalt or asphalt sealer. Sanitizing hand wipes with alcohol as their key ingredient should also work.
Alcohol should not damage asphalt, especially if it has been in place for a while, or asphalt sealer, said Chad Hopkins, lead estimator for AC Paving, a company in Millersville, Md.
Carol Chapin, vice-president of research and development for Simple Green, which makes cleaning solutions, suggested wetting a cotton ball with acetone nail polish remover and dabbing that on the pitch to soften and remove it. Or, she said, you could use a petroleum-based hand cleaner. After you apply either of these, she suggests you wash the surface with a solution of 10 parts water to one part Simple Green All-purpose Cleaner, available at Wal-mart and other locations.
It's also possible to use undiluted Simple Green to dissolve the pitch. This approach might save you from having to spot-treat every place where the pitch dripped.
However, it's important to test first to ensure you won't damage the surface. Simple Green is a degreaser, and asphalt is a petroleum product. Depending on how the surface is sealed, the cleaner could break down the oil in the pavement.
“Changes in air-quality regulations have caused changes to the formulas of coatings such as asphalt sealers,” Chapin said via email. “Some are not as impervious to cleaners as they used to be.”
To test whether you can safely use Simple Green, soak a cotton ball or a sponge with the cleaner, and place it on the pavement in an inconspicuous area. After five minutes, remove the swab, and rinse the area thoroughly with water. Once it dries, check whether the spot has turned brown, and press with your finger to see whether the pavement is softer or pitted. If no change is evident, proceed.
The Simple Green website (simplegreen.com) details how to use undiluted Simple Green to remove tree sap from cars: Wash the surface. Apply the full-strength cleaner to a clean washcloth or terry cloth. Let the cloth sit on each spot for at least 30 seconds. Gently scrub with a soft-bristle brush or a non-abrasive scrubbing pad. Rinse.
The website also gives instructions for cleaning an asphalt driveway: Dampen the surface. Pretreat heavily soiled areas with the full-strength cleaner, and wait 10 minutes. Mix about 1 1/2 cups (375 ml), of cleaner per gallon (4.5 litres), of water, then spray or mop on. Scrub and let it soak for a few minutes. Rinse so the run-off goes into gravel, soil or landscaping.
If your test comes out OK, you can apply these instructions to removing sap from your walkway. Instead of pouring undiluted cleaner on the path, you might want to adapt the idea of leaving a saturated washcloth on the pitch spots; you could substitute an old hand towel or other thick rag that's bigger than a washcloth.
There is one huge caveat about cleaning asphalt, Hopkins said: “Do not — do not! — power wash with high pressure. If it's too high, it could blast some of the sand out. Asphalt is not like concrete, where you can really get in there and blast it.”
The warning applies even to asphalt topped by sealer, he said, because a high-pressure washer can blast off the coating.
If you do resort to using a pressure washer — and many homeowners do, especially for large expanses such as driveways — it's critical to use a wide, fan-type tip at a distance. “Go for the biggest spread, and keep the tip far away,” from the surface, Hopkins said.
The website pressurewasherwiz.com recommends keeping the tip three to four feet (. 9 to 1.2 metres), from the surface, which, for many people, is around waist height. The other alternative that this
site recommends is outfitting the pressure washer with a flat-surface cleaner, a circular head that cleans a wide swath in a single pass. Sticking with a hose is safe, and it's probably all you need for cleaning a path.