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The "How" of Car Washing - Understanding the Science of Wash Chemicals


The chemicals business has evolved in many ways, including car-wash-specific chemistry and industry-specific raw materials, as opposed to repurposing cleaners designed for other industries.


This is probably one of the most misunderstood details of wash chemicals. A home product like baking soda or other degreasers are examples of high-alkaline chemicals, while cleaners like lemon juice or vinegar have lower pH and are types of acids. Alkaline chemicals are best for cleaning organic soils like grease, for example, versus acids, which work best on inorganic soils like lime deposits, salts and clays. Maintaining the ideal pH balance results in a cleaner car.


The goal is a clean, dry and shiny vehicle. Achieving this requires the right balance of the following five factors:

1) Mechanical action, which is the effect of friction from anything that physically touches the vehicle, including water. The more dependent you are on mechanical action, the less dependence on other factors, and vice versa.

2) Water quality may be the most important factor, and it's also a common source of problems. Water quality affects the efficiency of the chemicals. We must consider hardness, which affects foam thickness, as well as total dissolved solids, which impact water spotting. In our experience, most sites benefit from a water softener.

3) Temperature of the car, water and bay is an important factor. Cold water slows the effectiveness of chemicals, although, as with other factors, there can often be a trade-off. If most of your cleaning is accomplished by friction, you need less heat.

4) Time is also important the longer chemicals sit on the vehicle in the bay the better the results. You can slow down the speed of an automatic wash to get a cleaner vehicle, but this reduces your throughput. There are other ways to compensate for the speed such as additional equipment.

5) Chemistry is an important factor for obvious reasons. This is a broad topic, including pH balance and the sequence of application. Helping you consider and adjust all factors is one of the benefits having a good working relationship with your supplier and their soap technicians.


Creating a great show for your customers is important. We recommend that you regularly check your end product. Stand at the end of the automatic wash and watch the cars that come through, ensure everything is working and the end result looks good. That's one of the first things our soap technicians do when they visit a wash, and it usually helps identify the source of any problems.

Excerpt from the “The How of Carwashing" podcast

Date Published: 11 July 2017