Professional carpet cleaners have a difficult and thankless job. Every month to six weeks, businesses in the city will be visited by these afterhours\' teams of men and women. The work starts the moment they arrive. Tables are moved and chairs turned upside down. Floors are often swept to clean up excess debris in preparation for the industrial strength cleaning. Rug and carpet cleaners then asses the type of carpet in order to pick a cleaning method. More often than not, these night owl cleaners have a bag of tricks that breaks down like this:

Carpet Shampoo Method
The theory in the shampoo method is to generate a lot of foam in the carpet, allow this foam to dry, have the resulting residue attract the soil, and vacuum up the residue and soil the next day. Most carpet shampoo systems are characterized by high foam levels that have a high degree of lubrication to minimize damage to the carpet fibers from the cleaning brushes. Carpet foam is important in order to pull particulates away from carpet fibers. The most common ingredient is sodium lauryl sulfate or one of its relatives. Sometime when you\'re taking a shower or bath, look at the ingredient statement on your hair shampoo bottle. It will say \"Contains sodium lauryl sulfate\" or some similar wording. Sodium Lauryl Sulfate and its relatives exhibit very high and very stable foam and are only mediocre detergents. The problem is that they dry to a soft, sticky residue which will cause recoiling.

Because of the re-soiling problem, carpet shampoos will frequently also have anti-re-soiling additives such as a resin to reduce this re-soiling tendency.
Many shampoos are actually very poor detergents and basically simply bury the dirt, they frequently also contain high levels of brightening agents which take invisible ultraviolet light and convert it to visible light, thus making the carpet appear cleaner and brighter than it really is, for a while. It will eventually give the carpet a pale yellow cast and this usually cannot be removed.

Shampoo methods are inferior due to poor cleaning plus re-soiling problems. The Rotary Shampoo method can damage the carpet, especially cut pile (which is what most residential carpet is).

Dry Cleaning Techniques
In this method, dry absorbent compound (containing small amounts of water, detergent, and solvent,) is sprinkled over carpet or worked into the carpet with a machine. This purpose of this cleaner is to attract and absorb soil. Mechanical agitation from a brush works the cleaner through the carpet.

These products usually contain an absorbent carrier, water, detergent, and solvent. The theory is that the liquids dissolve the soil and this soil/detergent/solvent mixture is absorbed into the carrier and is then vacuumed up. They are often used with a detergent pre-spray in heavily soiled areas.

The absorbent cleaner most commonly is organic, but may also be polymers. The compound is supposed to absorb the dislodged soil and is then vacuumed away. Carpet must be thoroughly vacuumed before and after cleaning.

Very thorough vacuuming should be used to ensure that most of the carrier comes out of the carpet. With the extremely fine powder types, indoor air quality can be reduced. If a white powder starts appearing on shoes and cuffs of pants, too much was used and it was not thoroughly vacuumed up. A common problem is for this white powder to reappear after wet extraction cleaning.
This cleaning method has the advantage of no drying time for interim maintenance, since little water is used. This makes if a common maintenance cleaner.

Carbonated Cleaning
This method is sometimes called \"dry cleaning\", which is a misnomer, since water is used. This method for carpet maintenance consists of the use of a rotary or oscillating brush adapted with a stiff brush or drive block designed to drive wet, damp or dry pads. The carpet can be sprayed with the cleaning solution and/or the pads can be soaked in the cleaning solution and squeezed lightly before placing the pad under the driving brush.

This method has very limited capability for soil removal and leaves much of the detergent in the pile since it employs no real extraction. As a result, rapid re-soiling often occurs. Another disadvantage is that the spinning bonnet may distort the fibers of cut pile carpet, fuzzing the pile and leaving distinct swirl marks.

Sometimes, carbonated water is used to supposedly give better soil suspension and bring down the pH. Companies using this method frequently use \"scare\" tactics to convince consumers that extraction cleaning or steam cleaning will destroy the carpet.

External Extraction
This method has fewer drawbacks than all of the other methods. Consequently it is among the one most often used. Often called \"Warm Water Extraction\", \"Hot Water Extraction\" or \"Steam Cleaning\" and is the cleaning method nearly all carpet manufacturers and carpet fiber producers recommend.

This is the only cleaning method classified as \"deep cleaning\". All the others are considered \"light surface cleaning\" because they are incapable of removing soil deep in the pile. Also, all other methods leave large amounts of cleaning agent in the carpet after cleaning.

This method is frequently called \"steam\" cleaning due to the fine spray of water used to force dirt out of the carpet which is sucked up by the vacuum slot immediately in front of the spray. Seldom is real live steam used, however. This process consists of spraying a solution of water and detergent into the carpet pile and recovering the water and soil with a powerful vacuum into a holding tank.

A freshly cleaned carpet sends a strong subliminal message of \"newness\" or a feeling of renewal. It\'s also healthy and often mandated - most notably in the food service industry - by health department regulations. While most of the world is going to bed, professional carpet cleaning crews are beginning their work day.

Perhaps no other group is more trusted to gain unsupervised entry into private businesses and use their expertise to remove grit and grime from the world\'s carpets. Perhaps no other form of interior cleaning adds more value.