Auto Laundry News - October 2012

Dirty Car Dangers — Choose Safe Cleaning Chemicals and Techniques

By Keith Duplessie

The motorist usually wants a clean car because of pride of ownership. But, are you educating your customers and potential customers about the dangers a dirty car presents? Any kind of dirt, or road film if left on a vehicle, can harm the painted finish. If dirt is left on the paint for a long period of time it can etch the finish or accelerate oxidation, and if someone brushes up against the vehicle it can cause marring or, worse, deep scratches.

Any dirt, grease, or grime on the finish is dangerous to the car including silica-containing material in ordinary dirt and soil, fuel exhaust, mosquito spray, salt- and ice-melting liquid sprays, slough from spent tires and other vehicle parts, as well as organic material such as oil drippings.


Chemical manufacturers face challenges in developing cleaning products for removing all types of dirt from the finish of a vehicle without damaging the paint, glass, and plastic. They must walk a tightrope in
developing products strong enough to remove the dirt, yet safe enough
to use.

There are also a number of variables that have to be considered when developing these chemical products: water pressure, water temperature, hardness or softness of the water, the angle of the pressure nozzle used in cleaning, as well as the type of chemical.


While individual detailers and car washers have their own opinions about the effectiveness of one process over another, it is an undisputed fact that the process begins with the application of a good chemical since various soils prove a challenge in removal.

Two-Step Acid-Alkaline Cleaning Process
Experts agree that this cleaning method is one of the most effective to remove dirt and road film. There are a number of formulas available for both the acid and alkaline solutions.

Such a system uses the acid solution to set up a static charge on the vehicle. Then, the alkaline solution is attracted to the acid solution, and the entire solution evens itself out over the vehicle. The surfactant portion of the alkaline solution burrows into the grease deposited on the vehicle. As the burrowing occurs, the road film is placed in suspension and is removed during rinsing.

That is for the oily portion of the soil. Other materials in that solution take care of the minerals, which are also part of the dirt film. This can include calcium, magnesium, or limestone found in the composition of some road surfaces. The films these minerals create on the vehicle are difficult to remove. Ingredients in the chemical formulation help dissolve the minerals or make them water-soluble so they can be removed with a pressure washer.

Take a very diluted acid solution and spray it on, and then, while the surface is still wet, spray it with an alkaline solution.

The acid dwells for a short period before the alkaline solution is applied. Another function of the acid solution is to get better distribution of the soap and water solution on the vehicle so that it is more evenly applied. In theory, you can use less soap. You don’t let it dry between applications, however. The various forms of alkalines used have a high pH, maybe in the 9-11 range. The pH scale runs from 0 to 14. At 7, a chemical is considered neutral; anything below 7 is acidic, anything above 7 is alkaline. The lower the pH, the more acidic. The higher the pH, the more alkaline.

Alkaline Cleaning
This method of removing dirt uses an alkaline cleaner mixed with water in a pressure washer. Some washes are very successful using this method. It basically works the same way as the alkaline portion of the two-step system. You have the surfactants with the heads and tails to take care of the grease, and you have the other detergents in there to take care of those hard minerals.


Even the best detergent in the world, if not applied correctly, won’t provide the results desired. A general rule of thumb is that the warmer the temperature, the faster the chemical reaction will occur.

So, if you use hot water, the result is faster cleaning and/or you could use less soap to get the job done. Even within this rule of thumb, variables exist. It is not just the water temperature. If hot water is used on a cold vehicle, the end result is a cleaning job accomplished with cold water. If the situation is reversed, the results are reversed. The temperature of the water, soap, and vehicle should be warm to work more effectively.

When choosing an effective washing system, it is important to know whether the water is hard or soft. This will have a notable effect on the outcome. Chemical suppliers will test your water first, because there is virtually no chemical that will work in hard water. If the water is hard, the first thing that needs to be done is to install a water softener. Alternatively, use only soft water purchased from another source.


Proper cleaning techniques also make the difference between a nice even, squeaky-clean vehicle or a streaky-clean vehicle. You need to apply your shampoos from the bottom up. This way the surface remains wet. If shampoo runs down onto a dry surface the alkalinity of the shampoo can change the pH of the surface. With a longer dwell time, the chemical will clean exceptionally well in that area and streaks can result. While cleaning from the bottom up assures that everything beneath is clean, rinsing from the top downward keeps the surface free from any residual soap or dirt.

Some believe pre-rinsing is not necessary since it creates a barrier between the dirt and the chemical when applied. Once the pressure and heat reach operational levels in the pressure washer, point the wand toward the ground until the soap-and-water solution reaches the end of the wand. Mist the car, holding the nozzle about two or three feet away from the surface. Work quickly so the starting point is reached within 30 seconds after the work began. By this time, the dirt should be starting to move. Now wash by holding the nozzle four to six inches from the surface. Move the wand left to right across the vehicle, from bottom to top as if you were painting horizontal stripes on the car. Then turn the wand sideways and “stripe” the vehicle vertically from top to bottom. This method is called the “waffle stroke.”

Flat surfaces should not be sprayed head-on, since this will cause the dirt to burrow into any wax on the surface. Position your arm and wrist so the “V” of the water hits the car at an angle and knocks the dirt away, not in.

If you have a thick layer of dirt, the shampoo might have loosened the dirt and film enough so that the angled water acts like a razor blade and will remove the dirt and film.


Dirt is a challenge to eliminate and some systems work better and in more applications than do other systems. Brushing with a good cleaning chemical works all of the time, and if you go through a car wash that uses soft cloth or foam material you shouldn’t be left with too much dirt on the vehicle.

Note that washing with either mechanical or hand methods to remove road film can have drawbacks. The dirt particles can become trapped between the wash material or hand wash-mitt, causing the vehicle to become scratched. There are pluses and minuses to any cleaning system. The paint and the vehicle surfaces always have to be considered when you are choosing a chemical and a cleaning method.


So how can you feel comfortable that you have chosen the right combination of chemicals and cleaning methods for specific cleaning jobs? Do the necessary homework. Part of your responsibility as a professional is to become knowledgeable about the chemical products and cleaning methods available. Work with a company that is honest, conscientious, knowledgeable, and reasonably priced. If they are an effective provider, they will evaluate each cleaning task and recommend the right combination of these choices. They should integrate a pressure washer, a cleaning formulation, and a method of performing the task so that the customer will enjoy the benefits of the most efficient vehicle-cleaning system.

Keith Duplessie is technical services manager for Portland, OR-based Detail Plus Car Appearance Systems.

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