There are three ways to wash a car: chemical, friction, and high pressure. Do we all agree? Send me an e-mail if you know of more, but these are the three I want to focus on in this article.


If you have a touch-free in-bay automatic, you count on high pressure and chemical. Let’s expand a bit: are the cars coming out as well as you would like — clean, shiny, and dry? If not, keep reading; there is always room for improvement.

Document comments and complaints to establish a trend.

The formulae to correct any issues you may be having with the wash quality in a touch-free in-bay automatic are fairly simple. The problem is either an issue with the chemical or an issue with the equipment, i.e., the high pressure. You are probably already aware of this, but it’s good to remember that, when you are having a problem with wash quality in any system, the chemical rep loves to blame the problem on the equipment, and the equipment rep loves to blame the problem on the chemical. I don’t blame anyone; I just want to put out the cleanest, driest car possible.

Not Dry Enough

Let’s touch on one common issue that confronts many in-bay automatic operations. The cars are coming out clean but not as dry as you would like. You have tried many different drying agents but have not seen a big difference. Here is the secret: it’s not a fault of your drying agent. Often, your step two in an in-bay automatic is high pH, then a neutral foam or triple foam. The problem is you are not getting the pH level of the chemical on the car back down to neutral before applying the drying agent. Drying agents do not break well when the pH level on the vehicle surface is too high. This can apply to tunnel washes, too, as you will read later in this article. If your system requires that you use a HP detergent in the wash process, you need to make sure you are using a low-pH soap (not neutral, low pH) afterwards to reduce the pH and alkalinity levels on the car. You will see an amazing difference in how dry the cars are.

Dirt Stripes and Clean Streaks

One more example in a touch-free in-bay automatic wash system: the cars are coming out mostly clean but some vehicles still have a stripe of film down the side, or the back around the license plate, or you see clean streaks running down the sides of light-colored cars after the wash. This can result from a combination of chemical and high-pressure issues. Sometimes the nozzles or applicators that apply the pre-soak, step one, and step two are not hitting every spot on every car. Nozzles with a narrow spray pattern cause a gap between where the chemical hits the cars as they pass. Then, when the HP blasts the vehicle on the next pass, it’s only hitting it with water. Remember, the chemical cannot work if it’s not on the car. To correct this problem, you may need new nozzles, a wider spray, or an adjustment. Sometimes the HP nozzles do not hit every spot on every type of car. There are so many shapes and sizes of vehicles out there, it’s tough to make sure every spot is covered. Make sure you watch the cars as they come out and document any comments or complaints you may be getting, this will show you a trend.


Friction rollovers and cloth or foam tunnel washes have a little more to worry about when it comes to wash quality. The issues can be chemical, cloth (friction), and/or high pressure or lack thereof.

Some tunnel washes do not have high pressure; the system must count on friction and chemical to do the work. Remember, the cloth only removes the dirt and film that has already been lifted off and put into suspension by the chemical. In other words, if you see areas on a vehicle that are coming out with dirt or film on them and you know that area has been hit by a wraparound or side brush, then you can be sure it’s a chemical issue. The detergent is not breaking up and lifting off the dirt and film so that the cloth or foam can swish it away and off the vehicle.

Friction Gap

On the other hand, if you see a two-inch dirty streak running horizontally on the sides of almost every car, you might be dealing with a friction problem. I have seen side brushes with a gap between the top core and the bottom core and, whenWater spots cannot occur on a dry car.the cloth is spinning and the car goes by, there is about a two-inch gap with the result that that no cloth touches the car. Without high pressure or other forms of friction to hit that area, such as a mitter or wraparounds, this streak will appear on some vehicles. While I was a manager of a car wash, I had customers show me these streaks and then proceed to wipe it right off with their finger. The customers says, “See, it came right off with my finger.” I reply, “Well luckily we do not wash cars with our fingers, but there is a problem and we will work on getting that corrected right away.”

Some car washes that offer towel drying make their towel dryers aware of the problem and they wipe the streak off manually. I am not recommending that, but I do know some car washes choose to handle it this way. I prefer fixing the problem, maybe closing the gap between the cores, or slowing the brush down and increasing the pressure just a bit, this will allow the cloth to lay down some on the surface and usually hits that gap and solves the problem.

Front-to-Back Mitter

Streaks up the hood and roof are other issues I see a lot in friction washes. This is why many operators tore out their front-to-back mitters and went to a top brush — going back to what we started with: a problem caused by either friction or chemical. Some will even argue that temperature is a factor in the issue as well, but I am not sure of that. If your front-to-back mitter is not getting all the dirt and film off hoods and roofs, you need to increase the strength of your detergent. Your soap needs more bite.

There’s not much you can do to improve the functionality of a front-to-back mitter unless you can speed it up or replace the cloth. Basically, the front-to-back mitter slides the cloth back and forth a couple times as the car passes underneath. If you are seeing streaks on the hoods and roofs of some cars, check the alkalinity of your pre-soak or prep-gun detergent. Some would suggest they would not want to increase the strength of their soap, thus using more chemical and raising their chemical cost per car for such a small percentage of vehicles having this issue. I agree, this is why many places install a thumb gun with a low-pressure pump such as a flo-jet, which then allows the attendant to manually apply a heavy-duty presoak to the very dirty cars that need the extra boost. Some chemical suppliers can hook you up with a product that will work great for this and also help in removing bugs from the front bumper and windshield.

Drip space is not as important as once thought.

A Drier Car

Another issue I see in tunnel washes, similar to the in-bay automatic, is the cars are still coming out wetter than they should and sometimes customers complain about spotting when the car dries. Here is the answer regarding spots: you cannot have water spots on a dry car. But yes, if the cars are coming out a little wet and dries in the sun, depending on how hard the water is or if the water still has some chemicals in it, spotting will occur.

Let’s talk drying agent again: sometimes setting your drying agent too strong causes the same result as not having it strong enough.

How you are applying the drying agent is not as important as whether or not the vehicle surface is ready for it. You can apply drying agent through nozzles or a rain bar but, as we discussed before, if the water on the vehicle surface is not at neutral or below on the pH scale, most drying agents will not function properly. Here are a couple secrets: as we are learning, drip space is not as important as we once thought it was. Chemicals have changed; we can get water to break almost instantly now if the chemistry is right. Car washes all over are now installing flash dryers, where the blower begins to remove the water in as little as six inches after the final rinse arch. Also, I have seen car washes with only one 10 hp top blower and one 10 hp blower on each side put out a dryer car than some car washes with a seven-, eight-, or nine-blower set.

I believe, in my experience, you need to get the water to break quickly and jump off the car as soon as the blower hits it, not pool up and make rivers where the air from the blowers just pushes the water around, back and forth. I went to one car wash where they offered towel drying. The manager told me the towels they use were terrible, they did not absorb the water well but just moved the water across the car when they wiped it. I tried it and he was right. The water just moved across the car and did not really get grabbed by the towel. He was running his drying agent very strong. Once I helped him get his pH levels back on track, not only was he able to cut way back on drying agent and the cars were coming out a lot dryer, but what water there was on the car was getting picked right up by the towel, and we could see a noticeable difference in the shine of the glass and chrome.


Whatever wash system you employ, getting it right is a fine-tuned recipe. When you take something away, you need something else to take its place. Car washes with a long tunnel and lots of friction can get away with cutting their cleaning chemicals way back, while a short tunnel with less equipment may need to spike things up a bit and understand that they need to set their solutions a little stronger to help in the cleaning process — and maybe even some high pressure would help. Just remember, it’s a balance, and sometimes it takes just a little tweak, maybe one tip size up, or reducing the pressure by 5 psi, to solve the problem. Having a good relationship with your equipment reps and your chemical reps is vital to your car wash success.

Chuck Lundberg, a 25-year car wash industry professional, is presently general manager of Clean & Green Car Wash of Marlborough, MA and owner of Independent Car Wash Consultants of NH. Chuck has served on the board of directors of the New England Carwash Association. You can contact Chuck via e-mail at