CHICAGO — Gritty debris, such as small sand particles, can stick to a car’s surface because of adhesion, especially when adhered with dirt or oil, and rub against a vehicle’s paint, according to

“Since sand is [several] times harder than the paint surface, it can mar the surface of paint jobs if left in place,” said Dan Pecora, owner of Erie Brush & Manufacturing, in the article. “So the grit must go.”

Black cars tend to show marring from grit more than other colors, reported the article, and 18 percent of cars in North America are black, according to a DuPont Automotive Popularity Report, which is the second most-popular car color after white.

“Since many of the carwash complaints come from grit-related paint marring, particularly of black cars, handling the issue can improve both your process and profits,” explained Pecora in the article. “Solving the grit problem can cost just pennies per car, and at the same time retain clients who may be worth $10,000 in lifetime business.”

Instead of using stiff and harsh cleaning brushes to remove grit, use softer brush filaments and better lubrication, “which together will help release grit,” the article continued.

Pecora noted in the article that stiffer filaments should not be used before grit is removed from both surfaces.