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Before the days of custom wheels, things were a lot easier for a detailer. Wheels were painted steel, the "hubcap" was chrome and cleaning was easy and relatively safe. All you needed was some soap, some agitation with a mitt or sponge and a rinse, and it did an adequate job. As for rust, an S.O.S. Soap Pad did the trick. And, there were not disc brakes spewing out brake dust on the wheel.
Unfortunately, those days are gone forever. Like today's automotive paint finishes, upholstery fabrics and leathers, wheels have become so sophisticated that most of the old cleaning products and methods for wheels are obsolete.
The science of wheel cleaning
Like paint finishing and carpet and upholstery cleaning, wheel cleaning involves a process that involves chemicals, tools and procedures to achieve a properly cleaned wheel with no damage.
To begin, a detailer must know wheels. There are so many types of wheels on today's vehicles, both O.E.M. and aftermarket, requiring that the detailer not make any assumptions without first testing to be sure what type of wheel they are working with.
The various types include painted steel wheels (that can be covered with an aluminum, chrome or ABS plastic wheel cover); chrome wheels (including chrome spoke/wire wheels); aluminum; magnesium (mag wheels); and clear-coated wheels.
Many of today's automotive wheels are clear-coated with polyurethane enamel. The coating is very similar to the clear-coat on paint finishes, except that it is thicker. The purpose of the clear-coat is to protect the wheel from oxidizing, staining or pitting and to make brake dust removal easier.
The clear-coat is usually only used on the aluminum or magnesium wheels because painted and chrome wheels do not require it.
However, not all aluminum and magnesium wheels are clear-coated just like not all paint finishes are clear-coated. Therefore, before working on a wheel you must determine what type it is and whether it is clear-coated.
To determine the type is easy. In most cases, it can be done visually. From a cleaning point of view, it is not necessary to distinguish between aluminum and magnesium because you would clean either the same way. The important thing is to know if they are clear-coated.
What is the best way to do this? Put a little non-abrasive polish on a white towel and rub the wheel. If it turns black, it is not clear-coated and you can proceed with caution. If it does not turn black, it is clear-coated.
After determining the type of wheel you are going to clean, then identify the problem. Depending upon the type of wheel, there could be several:
- Heavy brake dust concentration,
- Pitting (usually aluminum)
- Road paint
- Road tar
Wheel cleaning chemicals
After identifying the problem you can then choose the proper chemicals to do the job. There are several chemicals you would use to clean wheels.
- Acid cleaners
- Alkaline cleaners (usually called non-acid wheel cleaner)
What you use depends on the cleaning problem for each wheel. For example, brake dust may be only a problem on the front wheels, as many cars have only front wheel disc brakes. Some wheels with brake dust concentrations are relatively flat and easy to clean, so a less aggressive cleaner may be all that is required.
Another example would be the BMW or older Volvo wheels with heavy brake dust concentration; it can be a real problem to clean due to several recessed areas.
Listed are the items we recommend to clean wheels with:
- Wheel brush: There are two types, one with a stiffer natural fiber and one with a softer, synthetic fiber bristle.
- Spoke brush: For cleaning spoke wheels and reaching into recessed areas.
- Toothbrush: With a fiber not metal bristle.
- Detail brush: The same brush used for final detailing.
- Steel wool: But nothing more aggressive than "00" or better, "000."
The cleaning process
This of course, is determined by the type of wheel and the problem. It is very difficult to offer one procedure without specifying the type of wheel and the problem. As an example, I will pose a common problem:
The wheels: Original BMW wheels that we have determined are clear-coated with no chip or flaking problems.
The problem: Problem is a heavy concentration of brake dust. One wheel has road tar on it and some road paint.
The chemicals: Wheel acid, non-acid cleaner, solvent and paint remover.
Tools: Wheel brush — stiff, spoke brush, toothbrush and steel wool.
Procedure: Some of these steps are basic to cleaning all wheels. You have to determine which you will use for your situation.
- Always pressure wash the wheels to knock off as much dirt and dust as possible, and more importantly, to cool the wheel. Never apply chemical to a dry or hot wheel. This can cause streaking and staining.
- Apply wheel acid to the wheels. Follow this with an application of non-acid (alkaline) cleaner to neutralize the acid. On hot days, it is advisable to apply chemical to only two wheels at a time, or even individually if it is too hot. Allow the chemical to dwell and work for you, but do not let it dry.
- Take the wheel brush and scrub the flat surface of the wheel using a lot of water and getting the bristle into as many recessed areas as possible.
- Use the spoke brush and water to clean the deeply recessed areas of the wheel.
- Rinse with clean water and if there is still brake dust in the recessed areas, which is typical with BMW wheels, reapply the chemicals. Then use the toothbrush and/or a piece of steel wool to clean out the recessed areas. It is a lot of work and can take a lot of time, but if we as detailers cannot clean the brake dust off, who can? And, turning a car back to a customer with brake dust still on the wheels is like a carwash giving you back your car with dirt still on it. To provide quality work takes time, and time is money. That is why you must get a fair price for your work.
- Apply solvent to the road tar, let dwell and remove with a small piece of steel wool or a towel, whichever works best.
- Apply paint thinner to a towel and see if that will remove the road paint. If it does not, you may need to use steel wool to remove heavy paint concentrations. Always take care when using steel wool so that you do not scratch the wheel. Remember, it could be polyurethane enamel, just like the paint. Aluminum or magnesium wheels will also scratch if rubbed too hard with steel wool.
- Rinse all four wheels and they should be perfectly clean if you have done your job.
Remember this is only a case study. There are many types of wheels and hundreds of different problems. You must evaluate each and every situation with the same care and attention you would the paint finish.
Wheel cleaning chemicals
Of all the chemicals used in the detail business, wheel acids are the most dangerous to the wheel, the employee and the environment.
Many contain hydrofluoric acid (HF), which is quite harmful if you get it on your skin, in your eyes or inhale it. Therefore, you should always wear safety equipment when using wheel acid. This means glasses and gloves, and the work should be done in a well-ventilated area.
Non-acid wheel cleaners, while not as dangerous, have a high pH (10 to 12). They are harmful to your eyes and will severely dry out your hands if not used with gloves. So do not be fooled into thinking that they are not dangerous.
In addition, repeated use of wheel acid can break down the resin in the clear-coat and cause it to cloud and/or deteriorate. So use acid only when absolutely necessary.
And remember: Just because it cleans faster than non-acid does not mean you should always use it.
R.L. "Bud" Abraham is president of Detail Plus Car Appearance Systems, Portland, OR, and a nearly 40-year member of the car care industry. He is also the executive director of the International Detailing Association and a member of the Western Carwash Association Board of Directors. Abraham can be contacted at firstname.lastname@example.org.