“Two-Step” or “Twin-Chem” Truck Washing


In 1972 while on one of my first truck washing jobs I witnessed an event not explicable by natural or scientific laws.  Yes, I witnessed a Miracle.

A few weeks prior to that job I told my friend, Steve Gerimonte, a sales rep for a raw material chemical supplier, that I was going to start a job washing trucks at Stroeman’s Bakery in East Hartford, CT.  When I first saw the trucks, I noticed that the bottom rails of the trailers were unpainted aluminum and they looked terrible.  In fact everything looked terrible.  Stroeman’s was one of those companies who washed their truck once a year at best and naturally – they wanted them washed for nothing.

I asked Steve what he thought I should use to clean those disgusting aluminum rails. A few days later Steve stopped by the shop to drop off a hydrofluoric acid (HF) product that his company produced and sold to the metal plating industry. He said “try this but be careful!”

The next Saturday I showed up at Stroeman’s with the anticipation of being there all weekend just to wash 12 trailers.  Yes, they were that bad.  The first trailer I washed took 2-1/2 hours.  At $18.00 a trailer you can see that I was really making a lot of money.

I brushed and scrubbed that trailer body until it looked about 50% better.  I was so tired that I couldn’t scrub anymore.  Then it was time for those bottom rails and Steve’s magic potion – the hydrofluoric acid cleaner that he dropped off earlier.  I applied it with a downstream injector and after several passes the aluminum looked like new – or close.

I know!  I told you about witnessing a miracle so here it is.

So now I am ready for my next trailer.  Yes, I am exhausted but like most mobile washers I was determined to finish the job as best I could.  After a 10-minute break I fired off my pressure washer (the one I built – 1000 psi @ 3.0 gpm), picked up the wand and started soaking down the next trailer.  I soaked and soaked and soaked and nothing seemed to be happening.  Then I noticed that the bottom rail was coming clean.  Oh my God!  I have just sprayed acid all over the paint!  Within a split second I had already conjured up illusions of ‘having to repaint the trailer’, losing the account or even worse – a lawsuit.  My insurance?  What insurance?

I quickly removed the chemical line from the acid jug and put it in the detergent jug and began to spray soap over the acid hoping that I could get the acid off before too much damage occurred.  And there it was – THE MIRACLE.

Before my very own eyes I saw grease, dirt, oxidation, start running down the side of the trailer leaving behind a surface that resembled a new paint job.  At the time I was clueless as to what I had just witnessed.  The only thing I could think of was to keep spraying acid and then soap on every trailer on the lot. Remember the first trailer that took 2-1/2 hours?  Well the remaining 11 only took 2-1/2 hours and the looked ‘brand new.’

Yes, Twin Chem cleaning is, by far, the fastest and most effective method of cleaning almost every type of surface. It also leaves behind the nicest looking job.  But not many mobile truck wash companies utilize Twin Chem for fear of surface damage. Face it, just the thought of applying acid to a painted surface will create illusions of disaster just like it did for me at Stroeman’s Bakery. The simple truth is most acids formulated for twin chem truck washing will not harm painted surfaces. Glass, on the other hand, does require special attention.  It can be damaged if hydrofluoric acid is not applied and rinsed properly.  Phosphoric acid cleaners will not harm glass and is recommended over hydrofluoric.

The general rule of thumb is to use a hydrofluoric acid ‘step 1’ every fourth or fifth service in order to keep the rails and other exposed aluminum bright and shining. Using this alternating process will lessen the possibility of glass damage in the event proper precautions are not taken or mistakes are made.

Alternating with a phosphoric acid will provide an excellent acid/alkali surface contact reaction and keep the rails clean.  Another huge benefit of using a phosphoric acid as your step 1 is the appearance of unpainted aluminum. While hydrofluoric acid is the quickest it leaves the aluminum ‘frosted or dull’ while phosphoric acid leaves aluminum with a much more polished look.  Another benefit of phosphoric acid is that it is less dangerous to use.  The next time you drink a can of Coke look at the ingredients.  You might be surprised.


Remember ACID goes on FIRST and SOAP goes on SECOND over the Acid!

To start – hold the lance pointed upward and pull the trigger so you will be able to see which way the wind is blowing.  Always work with the wind.  For instance – if the wind is blowing left to right – work left to right.

When washing a trailer, we recommend that no more than ½ of the entire unit be cleaned at one time. For instance, you would not apply product to more than one side and either the back or the front.

Apply the acid from the bottom to the top. Applying the acid to the top aluminum rails prior to misting the entire surface will result in aluminum oxide that is removed from the top rail will lock itself onto the painted surface below. When this happens heavy brushing will be required.

After the painted surface has been wet down with acid, you will then concentrate on the exposed, unpainted aluminum trim. Hold the low-pressure chemical nozzle close to the top rail and quickly walk the rail until you reach the end. Move the nozzle to the lower rail and walk back in the opposite direction. When you reach the end of the lower rail – repeat the process. Once the acid has been applied you are now ready to apply the detergent.

When washing a tractor, you would clean one side at a time.  Wash the back and the frame on one pass and then other side, roof, hood and front on your last pass. In some situations, especially when the ambient temperature is above 90°, you may have to clean a smaller area in order to keep the product from drying.

Never apply hydrofluoric acid to the top of the tractor or directly to the windshield or wiper blades.  Once hydrofluoric get on the wiper blades it cannot be neutralized.  Every time the wipers are turned on the blades are rubbing hydrofluoric acid into the glass.  If you have washed tractors in the past chances are that you have seen the end result of the problem.  It shows us on the windshield where the wiper touches the glass.  When this happens, you may as well replace the glass.


At this point you will have to move your chemical line from the Acid container to the Detergent container.

When applying the detergent – repeat the steps utilized with the acid application with one exception – make one additional pass with detergent. Generally speaking, it will take twice as much detergent as acid for an effective Twin Chem Process.

When the detergent comes in contact with the acid you will immediately notice dramatic surface activity whereby the pollutant will totally emulsify and “roll off” the surface.

RINSING – Trailers

Rising is, without question, one of the most important steps in any type of cleaning process.  You want to get the product off the surface before it has time to dry.  If you will use our product Speed-X-777 (Part #SPE55) in your detergent mix.  This product will decrease your rinse time by 70%

Remember, upon switching your gun from “low pressure chemical” to “high pressure rinse”, you still have detergent in the line which will be discharged under high pressure. Rather than clearing you hose up high where you stand a chance of getting a high-pressure mist of soap in the air that can land on other surfaces that can be damaged if not rinsed it is best to clean your hose in the wheel or wheel well or on the frame.  Since these areas are generally the hardest to clean the high-pressure soap will make cleaning process a lot easier.

When rinsing the trailer start by “walking the top rail” very slowly to ensure that ALL chemical products and pollutants have been thoroughly removed so they don’t sleep-out and leave unsightly streaks after you have rinsed the rest of the trailer body. Once you are sure the top rail has been sufficiently rinsed – continue with the remaining area to include the wheels, tanks and frame which are always cleaned last.

RINSING – Tractors

Pay special attention to the roof and glass when rinsing tractors. Always rinse from the top – down.

You will find it next to impossible to thoroughly, rinse the roof and hood areas if you are using a “straight” lance. Make sure that the lance has a 45° bend at the nozzle. Failure to rinse the roof WILL result in glass damage. Since it is impossible to keep all cleaners off the roof it lays there until the water has evaporated leaving behind a chemical residual.  Through the night moisture brings that dried chemical back into solution. The next morning the driver gets in the tractor and the first time he hits the breaks that solution runs down over the glass and onto the wipers.  Now he hits the wipers to clean the residual off of the windshield and here starts the never-ending problem.  The chemical remains in the wiper blade and continues to ‘burn or frost’ the windshield every time he hits the wipers.  If you are not sure if the roof has been rinsed thoroughly – stand on the drivers or passengers’ side of the vehicle and look through the side glass and through to the windshield.  Hold the lance in a position so that the rinse water will be running down over the windshield. Rinse until you do not see “bubbles”.  You can only do this if you have a 45-degree adapter on the end of the lance.  Simply order our part number BRF634 and install in on the end of the your 48 or 60” lance then reinstall the nozzle.

Recommendations for Single or Twin Chem Truck Washing

Recommended PSI & GPM

2000 PSI · 5.6 GPM
Remember cold water works fine but hot water works even better!


Recommended Chemical Injector: 

EnviroSpec Super Suds Sucker (part number 1964) with a dual chemical metering valve (part number 1308 which will require 3 hose barbs part number BRF354)


Recommended Trigger Gun

EnviroSpec’s “YG4000S” (#1218)

On the inlet side of the gun install a “hose whip” (part number 1568) in order to take the hose strain off the gun when you are pulling it. On the end of the hose whip install a quick connect plug so you can connect the high-pressure hose.

Install a 3000 PSI ball valve (part number 1303) on the discharge side of the unloader (between the unloader and gun). Setting the system up like this will allow you to change gun/lance assemblies quickly when need be.


Recommended Lance

Single Pipe – Stainless Steel Lance

48″ for Tractors   #1248 with BRF634, 45-degree street elbow
60″ for Trailers   #1248 with BRF634, 45-degree street elbow

Each lance should have a 45° bend at the nozzle. To do this, use a 45° brass street elbow (BRF634)



All of our Detergent Products have been formulated around the “Twin Chem” Cleaning process and all have the proper pH balance range.  They provide superior performance with all acid cleaners use in Twin-Chem cleaning.

Specifically, we recommend…

PRODIGY – The industry’s #1 selling truck wash.  This product provides superior cleaning results either as a stand-alone cleaner or as step-2 in the Twin-Chem cleaning process.  Below are specialty variations of Prodigy formulated for specific jobs.

LX9 IGNITOR – specialty heavy duty truck cleaner with Lavender & Coconut

  1. MUSCLE – to be used when there is a heavy build-up of exhaust carbon.

BOND BREAKER – Formulated to remove all road film

VIPER – Superior product for white tractor/trailer bodies. Great product for heavy build-ups of exhaust carbon

CHISEL – Formulated for the initial cleaning of vehicles that have been neglected or are cleaned on a quarterly, semi-annually or annual basis.

For Further Technical Support Call: 1-800-346-4876