Professional Carwashing & Detailing

Super Soaping Solutions

October 11, 2010

Here’s my advice: dry the cars at your wash with soap.

Have I been out in the sun too long? Been exposed to very cold temperatures? Has someone spiked my coffee?

No, not at all. In many situations, the poor drying results that you may be experiencing can be solved by products other than drying/rinse agents.

Breaking tradition
If vehicles exiting a wash do not “break” as well as the owner thinks they should or are not as dry as he or she would like, the natural tendency is to increase the application of the drying/rinse agent.

Many operators assume that increasing the amount of drying/rinse agent applied to the vehicle will result in better break and drying.

But, many times the result becomes worse rather than better. You may be treating the symptom rather than the cause.

Drying/rinse agents are designed to increase the surface tension of the vehicle, causing water to roll off of the vehicle surface. This is the “water off a duck’s back” phenomenon.

When breaking and beading are less than optimal, operators try new rinse configurations; increasing or decreasing rinse water pressure and flow, slowing down the speed of the pass or the conveyor.

These are all areas that should be checked, but the drying problem may result from detergents that are applied to the vehicle.

How can this be possible? You use large volumes of rinse water, you can’t see any foam and the soap should be off the car.

But is it?
One of the functions of all presoaks, detergents and shampoos is to reduce surface tension, allowing the ingredients in the cleaner to penetrate into the vehicle’s soil.

If owners fail to reduce the surface tension of vehicle surfaces, their cleaners will not penetrate the soil and the result will be a car that leaves the wash as dirty as it came in.

Vehicle cleaners are designed to perform a task that is exactly opposite of the job of drying/rinse agents, so let’s explore this situation further.

Whether you operate a conveyor, in-bay automatic or self-service wash, the majority of time that the vehicle spends in the wash is in the cleaning portion of the process. We may prep the vehicle, then apply any number of presoaks and/or other detergents and shampoos and allow the cleaning process to continue.

Applying drying/rinse agents comes at the very end of the process and we expect to see water run off the vehicle almost instantly. If the water doesn’t run off as we expect, detergent carryover may be your problem.

Detergent carryover is a term that describes a situation where some of the detergent is still on the vehicle surface despite all the operator’s efforts to rinse it away.

Washable problems
Today’s vehicle cleaners are very concentrated products; a little goes a long way.

If a wash owner is applying too much detergent to a vehicle, even the high volume and pressure of the rinse water may not be able to dilute it enough to wash it away.

There are two situations where this can happen. One is in an in-bay automatic and the second is in a conveyor wash.

In some in-bay automatic and conveyor touch-free washes, operators apply either one pass of presoak, two passes of one presoak or one pass each of two different presoaks.

In order to allow sufficient time for the presoak to work, the operator may elect to immediately apply triple foam to the vehicle before the high pressure rinsing begins.

In theory, this is a great way to extend detergent “dwell” time without increasing the overall length of the wash.

On the other hand, when the high pressure rinse begins, it now has to dilute the triple foam, and one or both presoaks.

Although all the foam may be removed from the vehicle, an invisible film of detergent may be left on the vehicle.

When the drying/rinse agent is applied the surface, reducing tendency of the detergent counteracts the surface increasing function of the drying/rinse agent; the result is water that lingers on the vehicle surface.

Detergent carryover
In a friction conveyor wash, many operators start the wash process with an application of high pressure detergent through their prep guns.

The next step may involve hand detailing sections of the vehicle with brushes that are lubricated with a detergent of some type.

The vehicle then enters the wash itself, perhaps passing through an arch delivering a presoak and then continues to the friction section.

In the friction section, a foaming shampoo is generally applied and the car continues through the washing section, where a small amount of detergent is applied to the friction material for lubrication.

A large amount of detergent has been applied to the vehicle and, without sufficient volume of rinse water, detergent carryover may result, slowing the break and yielding a less-than-dry vehicle.

There are several approaches to resolving the detergent carryover problem. Check all nozzles, pumps and arches that are involved in the rinsing process to ensure that they are operating correctly.

Occasionally, in some in-bay automatics, check valves have failed and allowed detergent to seep into the rinse water.

Determining detergent needs
If an owner is still experiencing detergent carryover, the first call made should be to the detergent supplier.

They will be able to determine if the amount of detergents that are being used are in the acceptable range or if the owner is overusing detergents.

If a carwash operator is applying too much detergent, the supplier should be able to suggest adjustments that will eliminate detergent carryover without adversely affecting cleaning.

Also, speak to the supplier about detergents that are known as fast or easy for rinsing.

Acidic (low pH) detergents are popular with many operators because they clean well, add shine and aid the function of drying/rinse agents.

Recent developments in chemistry have given detergent manufacturers the ability to build detergents with all the cleaning power of their predecessors, but that are easier to dilute and rinse away.


Dan Kramer is the Technical Director of the Stone Soap Co., Inc. and has been with the company since the 1980's. His responsibilities include product development, product testing and instruction at the Stone Soap Car Wash Training Academy. Dan can be reached at dkramer@stonesoap.com.