The Science of Carpet Cleaning

The Science of Carpet Cleaning

For additional information see "Step by Step Interior Cleaning"

Detailers treat carpet cleaning like a "step-child" compared to the attention given to paint finishing procedures. However, carpet cleaning is just as important.
In one of the many trade magazines I read monthly an interesting article appeared about commercial carpet cleaning authored by M. Dixon, president of Dixon & Associates.
Many of the points mentioned in his article were quite relevant to automotive carpet cleaning and for that reason I borrowed from him for this discussion.
Three Kinds Of Carpet Cleaning

There can be three kinds of carpet cleaning that detailers should be aware of:

• 1. KEEP-UP Cleaning
• 2. CATCH-UP Cleaning
• 3. DISASTER Cleaning

Types Of Carpet Material

Commercially there are two types of carpet material: natural fibers such as wool or cotton and synthetic fibers, usually nylon, but also olefin, polyester and acrylic. There are also many types of carpet construction, but most is either looped or tufted nylon. The height and weight of carpet pile will affect appearance and color. Normally a shorter looped pile, using a tweed design rather than a solid color will reduce pile crushing and will hide soil better. For the most part automotive carpeting is nylon.

Back To Cleaning
There are two types of soil in a carpet: dry soil or oily soil.
Dry can usually be removed with a vacuum, but sticky soil is more complicated.
Depending upon the soil, oily soil requires the use of chemical and one of several removal methods.
Which chemical(s) and the method of removal is critical to how fast and how clean the carpet is when finished. A carpet has three separate dimensions, and the dirt you see is not always all there is to clean. The first dimension is the top of the pile. That can be cleaned easily with a vacuum. The second dimension is the pile itself.
The third dimension is the backing where all the dirt, sand and carpet-wearing "Nitty gritty" ends up.
As a professional, you must be aware of these three dimensions and have the chemicals, equipment, procedures and knowledge to clean them efficiently (fast) and effectively (clean).
Carpets that look clean, as you can now imagine, are not always as clean as they appear. In the commercial and residential carpet cleaning business there is a growing concern over what is called the Sick Building Syndrome (SBS).

This refers to illnesses caused by bacteria in carpets that creates many negative symptoms in humans. While the detail business has, in the past, only concerned itself with the appearance cleaning of carpets it is evident that, as professionals we need to be aware of all aspects of carpet cleaning to provide our customers the maximum service.

"Keep-Up" Cleaning

"KEEP-UP" Cleaning is done to cosmetically clean the top of the pile and a small part of the pile itself.
As mentioned, a vacuum will suffice for this type of cleaning. When completed the carpet looks clean. But, a more thorough job must be done on the pile and certainly where the "real dirt" has settled.
"KEEP-UP" Cleaning is usually dry, but to remove oily soil will require some moisture.

Limited Moisture
This can be accomplished with a small orbital tool and a terry bonnet. That's right, the same orbital used to apply and remove wax or sealant can be used to clean lightly soiled carpets.
First, thoroughly vacuum the carpet; next spray lightly with chemical and buff until the soil is removed. During the process, as the bonnet becomes dirty just turn it over.

Another method is to spray the bonnet with chemical and buff as explained above. As the bonnet becomes dirty turn it over, or you can rinse it out and reapply chemical before continuing.
Using this process some of the soil is absorbed into the bonnet and some stays in the carpet. This process cleans the top of the pile and some of the pile itself. But the "nitty-gritty" soil remains in the backing. Other KEEP-UP Cleaning methods using limited moisture are dry foam and dry granular methods. The latter method allows the detailer to spread moisture granules on the carpet, then work them into the fibers. The granules must set for 20 to 30 minutes to allow them to absorb the soil. After, vacuum the granules up.

"Catch-Up" Cleaning

This is the process of cleaning that most detailers are familiar with and involves several methods:

a. Hand Brush

b. Rotary Brush Shampooer

c. Soil Extraction

d. True Steam Cleaning

• 1. Water leaks that flood the car
• 2. Spilled milk
• 3. Animal urine
• 4. Cola spills
• 5. Spilled paint
• 6. Spilled gasoline

• 1. Always dry clean as long as it does the job
• 2. Then utilize limited moisture
• 3. Then wet cleaning

• Time is of the essence - get to the spot or stain ASAP
• Begin by removing excess solids
• Blot excess liquids, do not rub
• Always use a white terry towel
• Work the spot from the outside inward to avoid spreading
• Check carpet for color fastness
• If spot or stain is of an unknown source use a solvent spotter first
• If soil transfers to the towel continue cleaning until gone
• If no soil transfer occurs, spot with an all purpose spotter
• Grease, oil and tar can be removed with solvent-based spotters
• Protein and sugar-based spots are best removed with a water-based, all purpose cleaner
• Gum - use a gum remover
• Rust - use a rust remover
• When finished agitate the area, rinse and blot. A wet vac or extractor can then be used
• If you are shampooing the entire carpet begin the shampoo process after the spot or stain has been removed.

Hand Brush
This method has been around since motor vehicles interiors.
All it requires is carpet shampoo and a nylon scrub brush. A high foaming chemical either "slopped" or sprayed on the carpet, then the detailer uses a lot of elbow grease to scrub the carpets. The foam in the chemical encapsulates the dirt and brings it to the surface.
Once scrubbed carpets are vacuumed and fluffed up. But as you will see, leaving a tremendous amount of chemical and soil and soil residue in the carpet.

Rotary Shampooer
A relatively new innovation in the auto detail business, this method has been around in the commercial carpet cleaning business since the early 1930's.

Rotary Shampooing utilizes a small pneumatic (air) tool (electric tools are usually too large) equipped with a nylon circular scrub brush about 5" in diameter.
High foaming shampoo is sprayed on the carpet and then shampooed with the tool until clean.
The surface residue is then vacuumed up, but again leaving residual chemical in the carpet.
The advantage of this method is that it will really clean a soiled carpet fast, without the corresponding detailer fatigue common with hand methods.
But, the same question must be asked about where the dirt and shampoo go with the rotary method?
It remains in the carpet, down at the backing.
How can it be removed? Read on...

Soil Extraction
Unquestioningly the most popular method in cleaning business and fast becoming the leading cleaning method in is what is correctly called "DEEP CYCLE RINSE EXTRACTION" or "SOIL EXTRACTION".
This process is sometimes called steam cleaning, but this is a misnomer. The steam that seems to rise from an extractor nozzle is not steam but simply the vapors of heated solution.
Actual steam is no less than 212 degrees F.
In any case, a key to successful extraction is to use as much heated chemical fluid as possible because fluid is what really does the cleaning. Of course, if you use a maximum amount of fluid you must be able to recover the majority of it to have a clean carpet.
The chemical used in extraction is a very low foaming chemical with a higher pH.
While the extraction method is considered a one-step process where dirt and cleaning solution are removed simultaneously, in the commercial carpet cleaning business when using a high pH alkaline extractor chemical they often use a "sour rinse" with a pH of 4-5.
This removes the alkaline residue which can cause dulling or browning of the carpet. Sour rinse products carry names such as Non-Brown; Brown-Out or No Brown.
Before extracting you must thoroughly vacuum the carpet; spot any heavy stains; pre-spray the entire carpet and let set for 5 to 10 minutes (dwell time) to let the chemical work.
Now that you understand the extraction process you can see that it is absolutely necessary to use an extractor after either the Hand Brush or Rotary Shampooer cleaning methods.
If the extraction method itself leaves shampoo residue in the carpet think of the amount left by these methods that utilize a high foaming chemical.
If you are to be a true professional detailer you must have all these methods of cleaning available: hand, rotary and extractor, using a combination of all three in your carpet cleaning.

True Steam Cleaning
This method is different from the extractor method that is often incorrectly called "steam cleaning".
A European innovation this "mini steamer" heats water to 250 degrees F. and claims to clean with no chemicals or cleaning agents.
From what I have seen this steam is a "KEEP-UP" Cleaning method utilizing Limited Moisture similar to the bonnet buffing method described earlier.
The carpet cleaning attachment is covered with a terry bonnet that you rub over the carpet as the 250 degree steam flows thru the attachment on to the carpet.
It can also be used to clean upholstery and even windows and wire wheels according to the manufacturers. As dangerous acid-based wheel cleaners are outlawed by OSHA, a steam cleaner may be the answer to spoke wheels.
If you are an experimenter and interested in testing one of these Steamer Units they cost about $399.00 and up.

Disaster Cleaning
In the commercial carpet cleaning business this type of cleaning is a result of fire or flood damage and is considered restoration cleaning that presents special problems, such as disinfecting, deodorizing, and mildew stain removal.
This type of cleaning is intended to save the carpet rather than replace it.
In the case of automobile carpeting it is sometimes less expensive to replace the carpet than utilize intensive cleaning methods.
There are however a number of cleaning situations in the detail business that could fall under the Drastic Cleaning category:

Probably the easiest and best way to overcome these cleaning challenges is to remove the seats and clean the carpet out of the vehicle.
Unlike a commercial carpet that is installed with adhesive or tack strips and quite costly or impossible to remove, most automobile carpeting can be easily removed by taking out the seats.
Certainly you can attempt to clean these "disaster" problems with the carpet in the vehicle, but in my opinion it will require both hand or shampoo methods and absolutely and definitely an extractor system.

Post Cleaning
When selling the carpet cleaning to the customer always suggest a fabric protectant application to prevent staining.
It is almost the same as selling a guaranteed sealant for the paint. And, it is a money-maker.
The chemical cost is minimal and takes only a few minutes to apply.

Summary
In conclusion you can see that carpet cleaning is sophisticated, even more so, than paint finishing and 'requires proper equipment, chemicals and procedures.
Remember when cleaning carpets:

Remember clean looking carpets are not always clean.
Carpet cleanliness can be determined with a few passes of a quality extractor nozzle that has a viewer panel in it. Or, look at the solution in the extractor recovery tank.