by Stuart Hulsey

What’s one of the first things customers look at when they leave a car wash?  What is one of the top complaint areas customers have post-wash?  If you answered “wheels and tires,” you’re right.

Next to clear, streak- and spot-free auto glass, pristine, shiny tires and wheels are what customers want the most.  And for good reason.  Consumers today are spending hundreds and even thousands of dollars on expensive wheels and tires with fancy aftermarket features.  Like a newly-engaged woman who wants to show off her sparkly diamond ring, car owners take a sense of pride in the flash and pizzazz of a great set of wheels and shiny, black tires.

This is good news for wash operators, who can build their business on added tire and wheel cleaning services.  However, before adopting or upgrading to a new wheel and tire cleaning service capability, there are several things that wash operators need to know to select the right tire and wheel cleaning chemicals for their specific needs.

Wheels, Tires & the Dirt that Sticks to Them

The aftermarket wheel industry has grown tremendously over the last five to seven years, with new designs and materials – all of which affect how wheels are cleaned.  For example, magnesium, chrome and chrome plate all react differently to different cleaning chemicals.  Wire wheels, aftermarket spinners, and other contemporary wheel designs feature tight curves and angles that create difficult areas from which to remove road soil and brake dust.

Just as the type of materials used in wheel and tire construction will impact selection of cleaning chemicals, the nature of the dirt or soil on the wheels and tires is also important.  There are two main types of soils: organic (carbon-based soils from some organism that was alive at one time) and inorganic (non-carbon-based soils, i.e., never alive).  Examples of organic soils include grease, oil, bug residue, acid rain, abraded rubber and abraded asphalt (the petroleum part).  Examples of inorganic soils include hard water mineral deposits, brake dust and other metals, road salts, abraded concrete and asphalt (the rock filler), dirt, clays and dust.

Keep in mind that soil types differ from one area of the country to another.  In city driving, oils, road salts, abraded asphalt and concrete are typical problems, while in rural areas, dirt dust, clay, bugs and road salts are problematic.

Soils bond to wheels/tires in several ways.  Understanding these mechanisms is important to selecting the right cleaning chemicals:

• Magnetic—In the way that iron sticks to a magnet.
• Electrical Charge—Cars build up static electricity by passing through the air.
• Precipitation of Salts—As the humidity increases and decreases depending on the time of day, road salts can be deposited, dissolved and re-deposited on vehicle surfaces, resulting in a hazy appearance.  These salts can be tough to remove as the deposition/re-deposition process continues over time.
• Absorption of Clays and Dirt—Clays can be attracted to vehicles in the form of mud, dust, etc.  The clays then soak up wet soils, oils and greases, thus contributing to the soil load.

Cleaning Chemicals Evolve

Just as wheel and tire technologies and designs have changed over the years, so too have the chemicals used to clean them.  This evolution is most notable in the move toward less aggressive, less caustic chemicals, and products made with special additives to boost cleaning power and performance.

To understand how wheel and tire cleaning chemicals work, it’s helpful to understand where chemicals fall on the pH scale.  The pH of a chemical is measured according to a logarithmic scale of 0 to14.  Chemicals with a pH of 0 to 5 are considered acidic.  Stomach acid, lemon juice and coffee are common items with an acidic pH.  Inorganic soils and soils held in place by magnetic forces are most easily removed with low pH products.

Chemicals with a pH of 6 to 8 are considered neutral.  Natural stream water and milk would be considered “neutral.”

Chemicals with a pH of 9 to 14 are considered alkaline.  Bleach and drain opener are two examples of items with an alkaline pH.  Soils held in place by electrical charge are best removed with high-alkaline products.  Keep in mind that while all caustics are alkaline, not all alkaline solutions are caustic.

It is important to note that pH is not an indication of the concentration of a solution.  The proper method used to determine solution concentration is titration.

Alkaline wheel and tire cleaning chemicals include active ingredients such as sodium metasilicate (metso), sodium carbonate (soda ash), sodium hydroxide (caustic soda, NaOH), and potassium hydroxide (caustic potash, KOH).  Years ago, wash operators tended toward chemistries with significant amounts of caustic to “burn” dirt and grime off of wheels.  Eventually, the damage caused by use of aggressive caustics led operators toward acidic chemicals.  Operators should steer away from wheel/tire cleaners with a pH above 12.5 if they do not want a product containing caustic soda, which can damage wheels.

Acidic wheel and tire cleaning chemicals may include the following sources of acidity: citric acid, sulfuric acid, hydrofluoric acid (HF), hydrochloric acid (muratic acid), phosphoric acid, hydroxyacetic acid, and oxalic acid.

In general, acidic cleaners most always provide a clean wheel with relative ease, although the type of acid used will clearly affect the cleaning result.  The decision on whether or not to use hydrofluoric acid, which may pose a worker safety issue if not properly managed—is an individual decision that may vary from operator to operator.  But with new types of acidic cleaners on the market, hydrofluoric acid is used less and less these days.

Detergents and solvents are used as alternatives to caustic and acidic materials to clean wheels and tires more safely.  In fact, there are widely available, non-acidic, non-caustic alkaline cleaning chemicals that do at least 95 percent of what acids and caustics can do, especially when coupled with high-pressure water and friction.  The ideal wheel/tire cleaner would have a detergency and solvency component with no caustic soda and a pH of less than 12.5.

Solvents—butyl and butyl substitutes, d-limonene, terpenes, and petroleum distillates—are often added to cleaning chemicals to increase their degreasing power.  Buffering agents such as complex phosphates, sodium carbonates, and sodium silicates also may be added to cleaning products to stabilize their pH during the washing process.  Some additives are seasonally specific—for example, to boost cleaning performance during dry seasons or when there is a lot of salt on the road.

Surfactants can either increase or decrease surface tension and improve wetting of the soil/surface, allowing better penetration of water to the soil and helping to prevent soils from being re-deposited on the surface.  It is important to be aware of the difference in the types of surfactants.  Mixing an anionic (negatively charged) surfactant such as a foamer with a cationic (positively charged) surfactant such as a drying agent or spray wax will cause them to neutralize each other and form a gooey solid that will stop up the application system.

Detergency and friction-based chemicals are best for salt deposits, while solvents are best used for absorption of clays, dirt and tar.

Eye on the Environment

The latest advances in wheel/tire cleaning chemicals can be found in those with environmental advantages.  Operators looking to be more earth-friendly may want to consider using chemicals that:

• Are produced via low-impact manufacturing that uses reduced energy and less water.
• Are concentrated products that reduce packaging materials, saving natural resources.
• Have less packaging and smaller containers to allow for more efficient distribution, resulting in lower fuel consumption.
• Contain earth-friendly ingredients (no chlorine bleach, phosphates, APE, or EDTA) to support water reclamation systems.
• Do not contain VOCs or other harmful ingredients, resulting in guilt-free, environmentally appropriate and more cost-effective disposal.

WATCH: Five Factors that Effect Cleaning

With so many different types of wheel and tire cleaning chemistries from which to choose, it can be difficult to match the right chemical and process to a specific vehicle.  That’s why it’s crucial for wash operators to properly train their sales people/greeters and employees to recognize, for example, not to apply a caustic wheel/tire cleaner to a magnesium wheel with no clear coat, but that it’s OK to apply an acidic wheel cleaner on a set of chrome wire wheels.

There are five factors that are crucial to understanding how wheel and tire cleaning chemicals work in a particular application:

Water quality, Action, Time, Chemical, and Heat.

Water Quality

Soft water is critical.  With hard water, cleaning chemicals need to “clean” the water before they can clean wheels, meaning more chemical is needed to get the job done.  Hard water problems can be improved with the use of chelating agents.  Also called water softeners, they are a type of sequestering agent used to remove metal ions from a solution, meaning they are also good for tackling brake dust.  Chelating agents such as Ethylene Diamine Tetraacetate (EDTA), sodium gluconate, and phosphate compounds do a good job of cleaning without the risks of caustic agents damaging a vehicle’s finish.  They are often found in “built” cleaners.

Action

Application equipment has evolved over the years to the point that highly caustic cleaners are not as necessary.  For example, poodle brushes have made wheel cleaning easier.  As have foaming CTA applicators.  High-pressure water that tracks the wheel movement produces a cleaner wheel than stationary pressure that depends on the wheel to pass by.  Maintaining proper service on high-pressure equipment will help ensure superior cleaning results.

Applications that use a wet foaming product tend to perform better than those that just spray from a v-jet nozzle.  Cleaning products with foaming action also allow for better cling time and make it easier for the chemical to get into tight areas that are difficult to clean.  While there is an added cost associated with the equipment used to produce the foaming application, less quantity of less aggressive chemicals can be used, thus helping to manage costs.  Foaming applications also provide a great customer “show” for locations with viewing windows.

Another decision to make here is whether to go with a friction-based system or a touch-free one.  Touch-free systems are ideal for short tunnel set ups.  They have a lower potential of damage to wheels and vehicle body than mechanical/friction methods, for better customer peace-of-mind.  However, touch-free systems also carry potentially higher chemical and labor costs and poor cleaning results.  Mechanical/friction-based systems, ideal for longer tunnels, carry potentially lower chemical and labor costs.  While there is a higher possibility of damage to wheels and the vehicle’s lower body with mechanical systems, these systems tend to result in cleaner wheels on a consistent basis.

Time

Many factors influence the recommended dwell time of the cleaning chemical, including the strength of the chemical (caustic vs. non-caustic), water quality and temperature, presence of high pressure, wheel quality and conveyor length and speed.  While chemicals with a shorter dwell time may allow for faster vehicle throughput and less potential manual labor, a longer dwell time typically results in a cleaner wheel and less wheel damage.  For high dwell times, look for foaming applications that cling to the wheel surface.  Remember that any time an extended dwell time is available, a less aggressive chemistry can be considered—an option that can also help to curtail costs.

Chemical

In addition to considering the chemical attributes of acidity, alkalinity, detergency, and solvency discussed above, wash operators need to decide whether concentrated chemistries or ready-to-use chemistries are best for their needs.  Ready-to-use chemistries do not require a water source, dilution equipment or special handling, and the cost-per-drum can be less than with concentrates.  However, each drum does not wash as many vehicles, so more drums need to be stored on-site.  In addition, with RTU chemistries, the operator pays to ship water—a component they already have on-site for much less cost.

Ultimately, the more concentrated the product, the less the end-use cost-per-car will be.  In addition to using lower-cost, on-site water, the operator is able to control the exact concentration needed, which can help to control costs.  Consider this: A concentrate diluted at 1:15 will wash 15 times more cars than a ready-to-use product.  Wash operators should ask themselves whether the RTU drum costs 15 times less than the drum of concentrate.  A qualified chemical supplier can work with operators to ensure the cost savings of concentrates, help with equipment maintenance and dilution management, and identify potential problem areas like leaks or pump malfunctions that can pump excess product down the drain.

Heat

The heat of the wheels being cleaned is also an important factor.  Heat can bake soils and brake dust onto a wheel to the point that it can not be removed.  On a 100 degree day, when a vehicle has been in traffic for an hour, the wheels should be cooled down with a water rinse before applying any chemical.  Applying chemical to a 150-degree wheel when dry will bake the chemical on instantly, thus damaging the wheels.

Utilizing heat from wheels in combination with a less aggressive cleaning formula can help prevent damage claims during extremely hot weather.

Alkaline and caustic or acidic and hydrofluoric?  These are just two of the questions operators need to ask when evaluating wheel and tire cleaning chemicals.  Wash operators should be encouraged to find a chemical supplier who can work with them as a true partner—helping them to understand the trade-offs among the many types of chemicals and application systems available today.  A simple product trial will help to determine if the cleaning efficacy, rinse ability and other performance factors of the products provide the strength needed.  Your chemical supplier also should be able to consult with you on how to meet local environmental regulations as well as employee training so that the chemicals chosen are used properly and effectively.

Stuart Hulsey is the vertical market leader, Southeastern region, transportation segment for Zep Inc. For more information visit www.zep.com.