Comparison of Carpet Cleaning Methods

Most carpet manufacturers recommend professional cleaning versus “Do-It-Yourself” for a variety of reasons. Your own, or rental, equipment may not be properly adjusted or cleaned and could cause problems such as the wrong proportion of detergents or cleaners which can leave residue and cause re-soiling,  over wetting, damage to rug fibers,  yellowing, etc.  Many rental units do not clean adequately and may actually damage your carpet.  The consensus of manufacturers and professional cleaners is that do-it-yourself methods work best as temporary treatments for high traffic or spill areas between professional cleanings.
In general, there are four basic methods for cleaning carpet:

    * Carpet Shampooing
    * Dry Chemical or Foam
    * Bonnet or Adsorbent Pad
    * Hot Water Extraction or Steam Cleaning.

Which system you chose depends on factors such as the carpet material, type of pile, wear, tear and the amount of soiling.  Some systems leave residues which promote re-soiling and defeat the whole purpose of cleaning. Some methods can actually damage the carpet fibers and shorten the life of the carpet. Check with the carpet manufacturer for recommendations. For a typical household most manufacturers recommend that carpet be professionally cleaned every 12 to 18 months depending upon the number in the household, amount and type of activity, and whether the carpet is light or dark. You should try to clean the carpets before they become too heavily soiled.  In spite of beliefs to the contrary, frequent cleaning will not cause the carpets to re-soil faster unless you use a method which leaves a dirt-attracting residue.
 
Shampoo:

 A wet shampoo/detergent solution is scrubbed onto the carpet through openings in a rotary brush, whose turning converts the solution into foam and works it into the carpet.  Once dry, most residue containing loose, encapsulated soil is vacuumed to remove it (although often dirt attracting residue remains). Chemicals may be added to the shampoo solution to reduce odors, retard soiling, brighten colors and/or speed drying which may also leave a residue. Sometimes this method is combined with Hot Water Extraction using water rather than a detergent solution to remove shampoo.  Although more expensive this method is especially effective for cleaning highly soiled carpets, with heavy oil/soil build-up.  Self-applied aerosols foams are a variation of shampoo.  The foam is usually sprayed onto the carpet and worked in rubbed in with a sponge or cloth. When dry, the residue containing suspended soil is vacuumed up. The foam uses little water and usually does over wet the carpet. Generally the foam does not clean as deeply as a wetter method and some foams may leave a difficult to remove residue which could cause problems with subsequent wet cleaning.

Dry Methods

Dry methods use dry chemicals or dry foams and are generally best for public or high traffic areas where a more thorough wetting could be a problem and they are typically used with periodic with deep cleanings. “Dry” is often a misnomer since quite some dampness may be involved. The process is fairly simple. First, because this method does not reach as deeply into the carpet fibers as a wet method, vacuum thoroughly. You might consider renting a commercial vacuum if yours is not very powerful (not only to pre-clean, but also to extract the dried foam and soil). If the carpet is heavily soiled you may wish to use a pre-conditioner to help clean it.  Then the chemicals are dusted into the carpet and worked in by brushing a number of times in different directions with a brushing machine.  After a short period of drying, usually about an hour, the entire carpet and floor surface are vacuumed.  The process can be repeated, if necessary, without damage to the carpet and will remove most surface soil. When using a dry foam machine always brush with the grain or flow of the pile if there is one.  This could entail turning it off and returning to the original edge of the carpet to foam an adjacent area going in the same direction.  When foam is dry vacuum it and the soil out. As potential drawback is that if not properly applied and removed the dry materials can act as dirt attractants.

Bonnet or Adsorbent Pad Method

The Absorbent Pad method of cleaning (often called bonnet cleaning) is similar to the Shampoo Method. It uses an absorbent pad ('bonnet') attached to the bottom of a rotary machine.  A detergent solution is sprayed onto the carpet and the rotary pad is used to agitate and remove the soil suspended in the solution from the carpet. When one side of the pad gets soiled it can be reversed. And when both sides are soiled, the pad can be replaced and later cleaned. Often, his method is used in regular maintenance of commercial buildings. Like the dry methods, Adsorbent Pad cleaning does not wet the carpet fibers completely and dies relatively quickly. For the same reason the method does not clean as thoroughly or deeply as wetter methods and may leave residues. This method may not be effective for carpets with a distinct grain or flow to the carpet pile.

Hot Water Extraction or Steam Cleaning

As with other methods you’ll get the best results if the carpet is thoroughly vacuumed and pre-treated, if necessary, prior to cleaning. In recent years the most effective steam cleaning method appears to be truck-mounted units. Either portable or truck-mounted equipment is used to spray heated detergent solution into the carpet pile at a high pressure and immediately extracted along with the suspended soil particles. The machine may employ rotary brushes or another agitating device to work the solution into the pile and loosen soil. Results may vary.  One reason truck mounted units function more effectively than portable units do is that they are powered by the truck's engine and not your residential electric supply.  Other reasons are that they provide higher solution temperatures and spray pressures as well as more vacuum power for full extraction. This method wets the rug and you must wait for it to dry completely before normal use.

As with most other home services, you get what you pay for and if it seems too good to be true, it usually is. Ask for and check references. Check industry or state organizations such as the Institute of Inspection, Cleaning and Restoration Certification (IICRC) or the Professional Carpet and Upholstery Cleaners Association (PCUCA) to locate professionals in your area.






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