The science of wheel cleaning
In the “good old days” wheels on cars were painted steel and a hubcap was made of chrome. Cleaning was easy and relatively safe. A little soap, some agitation with a mitt or sponge and a rinse were all you needed for an adequate job. As for rust? An SOS pad did the trick.
But those days are gone forever. Like today’s automotive paint finishes and upholstery fabrics and leathers, wheels have become so sophisticated that many of the old cleaning products and methods for wheels are obsolete; or they must be used with great care.
This article will outline the series of steps necessary to choose the right chemicals, tools and procedures for the job. Your first step, however, begins with identifying the type of wheel on the vehicle. There are so many types on the market — including O.E.M. and aftermarket — that a detailer cannot make any assumptions without first testing to be sure what type of wheel you are working with.
Types of wheels
There are various types of wheels, including:
• Painted steel wheels that are covered with either an aluminum, chrome or ABS plastic cover;
• Chrome wheels, including chrome spoke/wire wheels;
• Aluminum; and/or
• Magnesium (mag wheels), clear-coats; and
• Aluminum wheels that are painted with gray or black paint and clear-coated.
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 tarnishing or staining and to make brake dust removal easier. It 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. So before working on a wheel you must determine what type it is and whether it is clear-coated by putting a little non-abrasive polish on a white towel and rubbing the wheel. If it turns black it is not clear-coated and you can proceed with caution.
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 because oftentimes these wheels will have rock chips in the clear-coat, or may already have started to flake off. You must be aware of this before choosing your cleaning procedure because if the wheel is aluminum or magnesium, and the clear-coat is chipped or flaking off, certain cleaners may cause problems.
Determine the problem, the chemical and the tool
After determining the type of wheel you are dealing with you must then determine the problem. Depending upon the type of wheel, there may be several:
• Heavy brake dust concentration;
• Road paint; and/or
• Road tar.
After identifying the problem you can then choose the proper chemical, or 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)
• Shampoo; and/or
The type of chemical 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. Or some wheels with brake dust concentrations are relatively flat and easy to clean so a less aggressive cleaner may be all that is required.
After selecting the right chemical, you then must choose the correct tool. In our training program we offer detailers a wide choice of tools to make the job easier, faster, efficient and more effective. Some of the items we recommend to clean wheels with are:
• Wheel brush: There are two types; one with a stiffer natural fiber and one with a softer bristle.
• Spoke brush: For cleaning spoke wheels and reaching into recessed areas.
• Toothbrush: With a fiber not metal bristle.
• Detail brush: Same as used in final detailing.
• Steel wool: Either “00” or “000.”
The cleaning process
This 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. Therefore, I am posing a case study. A few details about the car:
• 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.
• The tools: Wheel brush — stiff, spoke brush, toothbrush and steel wool.
• The procedure: Some of these steps (listed below) are basic to cleaning all wheels. You have to determine which you will use for your situation.
1. 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.
2. Apply wheel acid (see: A warning about acids and HF below.) to the wheels. Follow this with an application of non-acid (high-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.
3. 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.
4. Use the spoke brush and water to clean the deeply recessed areas of the wheel.
5. Rinse with clean water and if there is still brake dust in the recessed areas, which is typical with BMW wheels, you need to reapply the acid and/or non-acid cleaner. Then use the toothbrush and/or a piece of steel wool to clean out the recessed areas.
6. Apply solvent to the asphalt, let dwell and remove with a small piece of steel wool or a towel, whichever works best.
7. 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.
8. Rinse all four wheels and they should be perfectly clean if you have done your job.
Remember this was 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.
A warning about acids and HF
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 (HF) acid which is extremely harmful if you get it on your skin, in your eyes or inhale it and is not recommended.
With any wheel acid, you should always wear safety equipment. 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 (12 or 13). 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.
Also, repeated use of wheel acid can break down in 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 email@example.com.