Professional Carwashing & Detailing

Soil extractors and cleaning carpets

September 12, 2011

One thing detailers get complaints about from both dealer and retail customers is wet carpets that end up moldy, creating a musty odor in the vehicle. Why does this happen? In short, improper cleaning procedures.

For years, the common method for cleaning carpets and fabric upholstery in the detailing business was to use a 5-gallon bucket half-full of water and "glug" in some shampoo, or better yet some degreaser, and then "slop" the water and chemical mix all over the carpets and upholstery and go at it with a scrub brush.

Along the way, some innovative detailers discovered that by using a carwash mitt saturated with the water/shampoo mix they could get even more water/shampoo on the carpets and upholstery right down to the backing and into the cushions. After scrubbing the water/shampoo mix into the carpets/upholstery they vacuumed the excess water with a shop vacuum.

What typically resulted (and still will) from this "faulty" method of shampooing was a number of things:

  • Damp carpet/upholstery that fogs up windows and leaves a moldy odor in the vehicle.
  • When the carpet/upholstery does dry, the dirt left in the fibers "wicks" to the surface leaving the material looking like it was never cleaned in the first place.
  • The shampoo and soil left to dry in the fibers of the carpet/upholstery leaves a sticky residue that immediately attracts dirt, which quickly re-soils the material (especially the carpet).

The inherent problem with using only a shop vacuum to remove the shampoo and water solution is that you leave shampoo and soil residue in the fibers. Think of it this way: If a person jumps into the shower, gets wet, puts shampoo in their hair, soap all over their body, then jumps out of the shower using only a towel to wipe the shampoo out of their hair and the soap from their body, what happens? The thought of doing that makes most people's skin crawl. You leave a horrible residue in your hair and on your body! Well that is what is left on the fibers in the carpet and fabric upholstery when you use only a shop vacuum to remove moisture. Obviously, you must first rinse the shampoo out of your hair and the soap from your body before you dry with a towel, right?

As well, this is what detailers must do with carpet and fabric upholstery using a soil extractor to rinse clean the shampoo and soil residue. Is it any wonder there are problems with interior cleaning?

To properly clean you have to know your soil

It goes without saying, in order to properly clean carpets and fabric upholstery a detailer must know the kinds of soil that they are dealing with. Otherwise, how can they know how to attack it and rid the carpets and upholstery of the unsightly contaminants? They cannot.

That said; let us identify the kinds of soil that are typically in carpets and on fabric upholstery:

a.) Dry Soil
b.) Oily Soil

Dry Soil: It is estimated that 85 percent of the soil in carpets especially and fabric upholstery is dry soil.

Oily Soil: Fifteen percent is oily soil attached to the carpet fibers.

It should be clear that a very thorough and deep vacuuming is done to obtain clean carpets/upholstery. However, many detailers still simply slop the shampoo/water mix on the carpet without vacuuming at all, or at best, do only a cursory job of it; incorrectly assuming the shampoo will get the carpets clean. All this does is turn the dry soil into "mud" which is even harder to remove with just a shop vacuum.

What is the process to follow?

If you insist your detailers use the following procedures, your carpets/upholsteries will be as clean as humanly possible:

1. Thoroughly dry vacuum the carpet/upholstery. Some use an air blower to help raise the dirt and grit out of the fibers.

2. Approach each stain/spot with the appropriate stain/spot removal chemical which can be:

  • Food stains
  • Tar and grease stains (gum)
  • Red dye stains
  • Coffee/tea stains (tannins)
  • Rust stains
  • Pet stains

Stains and spots are generally best removed by hand or, even better, with a vapor steamer that generally assures the detailer a 100 percent removal result.

3. Pre-Spray the carpets/upholstery with a foaming-type carpet/upholstery shampoo and let dwell to emulsify the oily soil on the fibers. Note that there is not a great deal of oily soil on the fibers, so it is not necessary to saturate the carpet/upholstery with a great deal of moisture.

4. Friction scrub with a hand brush or, better yet, a rotary shampooer tool which will cause the shampoo to foam up lifting the oily soil off the fibers.

5. Now is the time for the heated soil extractor to rinse clean the fibers of the oily soil and shampoo residue. Do not rub the nozzle back and forth like a vacuum; this puts too much moisture into the fibers. Start away from you and pull the nozzle slowly toward you rinsing the fibers of all soil. It is advisable to have a view window in the extractor nozzle so that the detailer can see when they have extracted all the soil from the fibers, with a window they will always know.

6. Some detailers will use the extractor nozzle to "dry" vacuum after the extraction process to ensure that they have gotten as much of the moisture out of the fibers as possible.

Choosing a soil extractor

If you agree that the above mentioned procedures are those that should be used and followed in cleaning and shampooing carpets and fabric upholstery, it is clear that you must have a top quality heated soil extractor to get the job done properly. How do you choose which extractor is best?

The following are some guidelines to follow in choosing which extractor will work best for you:

Cost: Purchase the very best extractor technology you can afford. Be certain to purchase a professional unit, not one of the low-cost residential units. They simply will not stand up to the rigors of daily use in a detailing operation.

Size of the solution tank: How many cars will be processed per day? You do not want to have the detailer stopping to continually fill the tank. Purchase an extractor with a solution tank large enough to last all day without refilling. If your shop's only doing one or two cars a day at a single location, you can get by with a 2 or 3-gallon solution tank.

Suction: You can choose between a two-stage vacuum motor and a three-stage vacuum motor. The three-stage has the most suction or lift. A two-stage is good, but the three-stage is better. The comparison might be between a V-8 engine vs. a V-6; they both will function, but the V-8 has more power. Do not be misled by dual-motor units. From a detailing perspective, you do not get more suction or lift from dual two-stage or three-stage motors. These dual-motor units are for residential cleaning where you may have to increase the length of the vacuum hose to reach up or down stairs without moving the extractor. The dual-motors maintain the suction with a longer hose, but do not give you double the suction/lift.

Heat: You have a choice between a tank heater and an in-line heater. The in-line is the best because it gives instant heat. The tank heater has to heat up the solution, sometimes taking 10 to 15 minutes. The in-line heaters with higher watts are best: 1,000, 2,000 and 2,400 watts. The higher the wattage, the hotter the solution, and heat increases the cleaning ability of the chemical.

Pump pressure: The typical pressure of an extractor pump is 100 psi, but you will find some at 150 psi. There are others offering up to 375 psi. However, 100 psi is quite adequate.

Vacuum and solution hoses: Most vacuum hoses have the solution line tied to the outside of the hose. That is acceptable, but you can get an assembly called "hide-a-hose", which puts the solution line inside the vacuum hose for easier vacuum hose use. Much easier to use.

Nozzle: You want a stainless steel nozzle because they do not wear out or break like plastic. You also want a view window in the nozzle so detailers can see the extraction of the soil.

Prices: Professional units can range in price from $650 to over $3,000, depending on size and features.

As you can see, cleaning carpets and upholstery is a science, and a detailer simply cannot clean them without the modern technology of an extractor and a process for cleaning.

R.L. "Bud" Abraham is president of Detail Plus Car Appearance Systems, Portland, OR, and a nearly 40-year member of the car care industry. He is also the executive director of the International Detailing Association and a member of the Western Carwash Association Board of Directors. Abraham can be contacted at