How Car Washes Work

By: Jeff Tyson

Soap Up

In this photo, you can see the tire applicators, the mitter curtain and part of the pre-soak arch.

­ Immediately after the eyes, most car washes have a pre-soak. This is an arch that conta­ins several small nozzles that spray a special solution all over the car. This solution does a couple of things:

  • Wets the car down before the application of any detergents
  • Contains chemicals that begin loosening the dirt on the car

A lot of car washes also have a set of nozzles arranged near the ground that are called tire applicators. These nozzles spray the tires with a solution designed specifically for removing brake dust and brightening the black rubber of the tire.


In this car wash, the car then passes through a mitter curtain. This is a series of long, soft strips of cloth that hang from a frame near the top of the tunnel. The frame is connected to a motorized shaft that moves the frame up and down in a circular pattern. This makes the cloth strips rub back and forth across the horizontal surfaces of the car.

The mitter curtain cleans the hood, roof and trunk of the car by swishing back and forth over the surface.

The next item in our car wash is the foam applicator. The foam applicator applies a detergent to the car that becomes a deep-cleaning foam on contact. The nozzles on the foam applicator, as well as most other spray systems in a car wash, can be adjusted to change the angle of the spray and the size of the opening. The foam is created by mixing a chemical cleaner, which varies between car washes, with water and air. There are usually separate adjustment controls for determining the exact mix of the three components. The chemical typically contains some coloring agent to make the foam more eye-pleasing and obvious.

You can see the foam created by detergent from the foam applicator.

With a good coat of foam on the car, let's move on to the scrubbers.