Grit can act like sandpaper, rubbing against the automotive paint jobs that car wash owners are trying to clean and shine. Gritty road debris, such as small sand particles, often stick to car surfaces due to adhesion, particularly when adhered with dirt or oil.

“Since sand is many 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 (www.eriebrush.com), a supplier of car wash brush and detailing supplies. “So the grit must go.”

While grit is a problem for any paint job, black cars tend to show the marring from grit more than other colors. According to a DuPont Automotive Popularity Report, 18 percent of cars in North America are black, and black is the second most popular car color after white.

“Since many of the car wash complaints come from grit-related paint marring, particularly of black cars, handling the issue can improve both your process and profits,” Pecora said. “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.”

The problem with cleaning black cars can be caused by the grit stuck in the stiffer, harsher cleaning brushes used at some self-serve and conveyor car washes. The solution is to use softer brush filaments and better lubrication which together will help release grit.

Eliminate the Grit Problem

While stiffer filaments have their place, they should not be used before grit is removed from both surfaces.

“Unless grit is removed from both the car’s surface and the brush filaments, the harder you push the more the grit can mar the paint,” Pecora said. “Shiny black paint is prone to such problems because every perceived blemish is more noticeable on its mirror finish.”

Handling the grit problem is critical not only because car wash owners want to retain customers, but also because nothing hurts business more than an angry customer complaining in person, or worse — online — in today’s social media world.

“No car wash owner wants to argue with a customer in front of other customers because it makes everyone question your quality and service,” Pecora said. “But the stakes are much higher with social media reputation apps like Yelp that drive business towards you or away from you. So car wash owners should not ignore the grit problem.”

While a complementary polishing of any area of perceived paint problem will quiet an upset customer, not every car wash has polishing operations. A far better solution for car wash owners is to eliminate grit before it becomes a problem. Using a softer brush with better lubrication can resolve the situation.

“The softer the brush filament used, whether microfiber, closed cell foam, or hog’s hair, the easier it is to release grit,” Pecora said.

According to Pecora, hog’s hair — actual hair that comes from hogs — is one of the softest materials for handling grit for a number of reasons.

“The hog’s hair has the smallest diameter tapered filament, which helps to make it the softest,” Pecora said. “Since it is soft, tapered, and feathered at the tips, it tends to release grit when properly lubricated and will not grind it into the car surface. Because of the taper, the hairs still retain stiffness for washing up close, if scrubbing is needed.”

Pecora, however, cautions against purchasing cheap brushes, which are typically imported from Asia. These products are usually stiffer, and less dense, than high quality domestic options and are unable to foam feed which removes grit.

Another aspect to consider is bend recovery.

“Stiffer filaments like polypropylene and polyester may lack sufficient bend recovery, so if a brush is flattened out it could drag the grit along the car’s surface, which is the last thing car wash owners want to do,” Pecora said.

In part, because domestically manufactured hog’s hair brushes are able to retain their original shape even when bent 90-degrees, some offer almost 50 percent more brush life than imported options.

Since proper lubrication can release grit as well, it is also important that brushes have enough wet foam holes to enable such lubrication.

In self-serve foam brushes, for instance, some brushes like Erie’s FoamMaster^® offer six foam holes on a typical 9-inch brush. This spreads the soapy foam far more thoroughly than brushes with typically two or three foam holes.

“A continuous flow of soap foam will help to cleanse grit and dirt from the brush head to provide a better cleaning,” Pecora said.

As a final word of wisdom to self-serve car wash owners serious about minimizing grit in their process, Pecora advises posting signs for customers to wash the grit from self-serve brushes and cars before use.

For conveyer car washes Pecora also advises washing the grit from brushes before use. In addition to this, during the wash, employees should use a tall drum dipping the brush head into the top of the soap solution and stroking the car a few times and then re-dipping the brush allowing the grit to fall to the bottom of the barrel.