Detailing - August 2006

Wheel Detailing, Part I Danger Lurks in the Quest for Perfect Wheels
By Kevin Farrell

Customers love clean and shiny wheels. Perfect-looking wheels really make their cars “pop.” A car with dirty or even damaged wheels can, however, detract from the look of an otherwise gorgeous automobile. Wheels are more expensive than ever, with many people installing custom aftermarket wheels for a more personal look. OEM wheels are becoming more attractive as well, and enhance the appearance of a great-looking vehicle. Care must be taken to protect this ever-increasing investment.

The cleaning and care of wheels is therefore extremely important in the overall look of a detail, and in customer satisfaction. As detailers, we need to fully clean all the wheels to make them look showroom new — without damaging them or ourselves, and without spending all day in the process. Sometimes wheel cleaning is quite a chore, and it can be quite dangerous.


Wheel cleaning can be an easy part of the detail, or it can be a nightmare. If you have ever damaged a wheel with a harsh chemical or injured yourself with such a product, you know the feeling. Moreover, if you have ever spent 20 minutes trying to get one wheel clean, you’ve experienced the extreme frustration that accompanies the effort. So how can we make wheel-cleaning safe, yet fast and effective?

Many detailers are deathly afraid of wheel acids — and rightfully so. These are harsh products that are dangerous to the wheel — and to you, if used incorrectly. Acids have hurt many people, and lots of wheels have been permanently damaged or destroyed. However, many detailers (including myself) continue to use products like these because of their effectiveness. Let’s look at the reasons for both acid’s effectiveness and its harsh effects.

It Really is Acid!
Acid is highly corrosive! The skull-and-crossbones warning on any acid label is there for a reason. It eats away at almost everything in its path. This is both good and bad in wheel cleaning. If wheels only had normal dirt on them, we could wash them with simple soap and water or a light solution of all-purpose cleaner. It’s not the wheels’ composition that sometimes necessitates the use of acid or harsh cleaner, but what gets on the wheels that needs to be cleaned. The car’s brake pads and the brake rotor itself are what cause the problems. Combine this with extreme heat and neglect, and the cleaning process becomes much more difficult.

As vehicles have become faster, bringing the vehicle to a stop has become more exacting. This job falls mainly on the brake pads. Today’s brake pads have become more of a metallic composition. This helps bring the vehicle to a quicker stop, while also prolonging the life of the pad and enhancing the ability to resist brake fade. There are also other organic compounds in the pad composition, as well as the gluing systems to hold them together. The throw-off of the shavings of the pads (which are very hot) and, to a lesser degree, little bits of the brake rotors (which also get very hot) onto a hot wheel results in deposits that bond themselves to the wheel. The more that gets on the wheel, the deeper it embeds itself into the wheel and the more difficult it becomes to remove. This “brake dust” will never be fully removed with soap and water. This is why harsher cleaners such as acids have been used for years.

What Acid Does
Acid basically attacks a surface and eats away at what’s in the way. Acids are very effective in dissolving metals — which brake dust essentially is — and breaking down the adhesives, far better than any other cleaner. But what makes acid so dangerous?

Let’s look first at the pH scale. The pH scale runs from 0 at the far left of the scale, to 14 at the far right. In the middle of the scale is 7, which is neutral. Acids are to the left of the scale and are less than 7. Alkalines are to the right of the scale and are greater than 7. The more a product moves away from 7 (or neutral), the more aggressive it becomes. Water is neutral and most car wash soaps range between a 7 and 8 on the scale. A neutral product rarely will remove any kind of embedded brake dust. Acids have almost always been the choice to dissolve and clean the brake dust. Not only would acids remove the brake dust, they would also brighten the metal alloys of the older style wheels. They are quick, yet highly caustic and dangerous. So why are acids still the choice for some detailers?

Let’s look at the types of acids that are in some wheel cleaning products and how dangerous they can be. Many companies use hydrofluoric acid (HF). This is probably the most dangerous form of acid out there. A 50-percent solution of HF can kill you if inhaled directly or if it is spilled on you. HF will only lightly burn your skin but the real problem comes later. It wants your bones! It seeks the calcium in your bones and in your blood! HF spilled on your skin may require calcium gluconate gel or an injection to replenish the calcium and ward off the effects HF causes. Its calcium-eating ability is the reason why HF is a popular choice in concrete cleaners.

HF is not the only dangerous acid used in wheel cleaning products. There are biammonium and ammonium fluorides. There is sulfuric acid as well as phosphoric and nitric acid. All are pretty nasty.

Detail shops, car washes, dealerships, etc. that have known about the bad things acids can do would sometimes switch to the other side of the pH spectrum and use an alkaline cleaner to clean the wheels. The phosphates and other harmful agents in alkaline cleaners can be equally as dangerous. They can still burn you and can still damage wheels.

These excerpts come from MSDSs for wheel appearance products.

Why All the Damage?
The problems with harsh cleaners lie in the fact that years ago the fancy wheels were alloys. They had no protective coatings, and the metal was exposed to everything thrown at it. The harsh acids or harsh alkaline cleaners would not only dissolve the brake dust, but the alloy wheels itself! Combine these harsh cleaners with people spraying a cleaner on a hot wheel, letting it soak in or dwell for awhile, and using the product in a highly-concentrated form and the cleaners would quickly etch — or eat right through — a wheel. Some wheels were more resilient — like chrome or painted steel. Aluminum alloys, however, would take a beating.

Almost all of today’s alloy wheels have a powdered clear-coat film, which adds the gloss and some durability to the wheel finish. Although the clear coat is more durable and will withstand the effects of harsh cleaners more than an unprotected wheel, long-term damage can still occur with the use of any harsh cleaner.


Not only is the type of chemical being used dangerous, its concentration level should be closely examined. As stated before, a 50-percent concentration of HF can kill you if spilled on your skin or directly inhaled. The percentage of acid used in the product will give you further evidence of just how dangerous the product truly is.

I have seen MSDSs of wheel acids where the concentration level of HF is slightly over 10 percent. I have also seen instances where the concentration level of sulfuric acid is almost 20 percent. These are very aggressive and dangerous products because of the high concentration levels of their acids. I have even encountered pH levels on some products that are at 1.0 or even less! This is about as low as you can go on the pH scale, as far as acidity is concerned.

After reading some of this information, you may want to run as far away from these products as you can — but wheel acids can still be used safely if certain precautions are taken. The first thing I look for is a product that does not have a high concentration level of any kind of acid. If the concentration level of HF even approaches 10 percent, I look for something else where the level is more in the 5-percent-or-less range. Sulfuric acids should be in the 10-percent-or-less range. This automatically makes the product less aggressive at the start. I also look for the pH level to be as high as possible. I don’t want anything less than a pH of 2.0 in any product I purchase. Remember, the more the number creeps toward the middle — or 7 on the pH scale — the more neutral it becomes, and the safer it is for both you and the wheels.


Of course, correctly and safely mixing any product — regardless of its composition — is very important. In the case of wheel cleaners — especially acids — it’s imperative to proceed with extreme caution. In mixing or diluting a product, always follow the manufacturer’s instructions specifically. If they say dilute it at 10:1, they mean it. That does not mean mix it at 2:1 or 3:1 to get the wheels “cleaner” or to get them done more quickly. Follow the instructions!

Acids used in wheel cleaners are water-soluble and will be much safer at proper dilutions. What should be understood about mixing acids with water is this: Water helps makes the product safer. For every tenfold you dilute an acid, you raise the pH by 1 point. This does not seem like much, but it’s huge. This is why you should purchase a product with a lower concentration of acid to begin with, and have a product with a higher pH.

Always wear eye protection and heavy-duty gloves, and cover your skin when using or mixing acids with water. Also, it’s a good rule of thumb to add acid to water, NOT water to acid! At lower-concentration levels, this is not a huge deal. But, in labs where they use high-concentration levels of acids, it very important to add the acid to the water. Here’s why: A large amount of heat is released when strong acids are mixed with water. Adding more acid releases more heat. If you add water to acid, you form an extremely concentrated solution of acid initially. So much heat is released that the solution may boil very violently, splashing concentrated acid out of the container! If you add acid to water, the solution that forms is very diluted and the small amount of heat released is not enough to vaporize and spatter it. So, always add acid to water, and never the reverse.


Most companies today either have — or are working on — safer wheel cleaners. They realize the importance of clean wheels, yet know the dangers of acids or other harsh cleaners and are working on alternatives. The problem has been that some safer cleaners won’t work quite as fast or fully remove the embedded dust that some wheels have. Check with your local supplier to see what safer wheel cleaners are available and give them a try.

When we continue our discussion on the subject of wheel cleaning in the September issue of Auto Laundry News, we will have set the stage for actually getting some work done! There are wrong ways and right ways to clean wheels, and we will be taking a closer look at both approaches. We will also offer some suggestions on how to get those wheels that present the greatest challenges sparkling again.

Kevin Farrell owns and operates Kleen Car (, a full-service auto-detailing business located in New Milford, NJ. Kevin is also an instructor for a detailing program he developed for, and in conjunction with, BMW of North America. His background includes auto dealership experience and training through DuPont, General Motors, and I-Car.

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