Cleaning soiled carpet fibers can be a real challenge since regular vacuuming does not remove particles which adhere to the fibers. The traditional way of cleaning the carpet fibers is the carpet shampooer which creates a foam that is worked into the carpet to clean it. While this method is still being used, the industry has been promoting the "steam" (hot water) extractors to a greater extent. There are also a few companies which sell or rent scrubbing machines which work a moist compound into the carpets to clean them.
A variety of hot water extractors are being marketed ranging from the large or small canister with hose and nozzle to those that look more like an upright vacuum cleaner. Their basic operation involves spraying a warm water and detergent solution into the carpet to wash the fibers and then extracting the solution and dirt from the carpet. Some even include rotating or revolving brushes to agitate the carpeting for better cleaning.
The earlier extractors which were sold consisted of a special wand and nozzle which was used on a wet/dry utility type of vacuum cleaner. A long hose was connected to the hot water faucet. Detergent in a small bottle on the wand was mixed with the water before it was sprayed into the carpet. A finger controlled valve enabled the user to control how wet the carpet became. This type of system is still being used by a few companies.
More modern extractors are more self-contained in that the water and detergent solution are placed into a tank in the machine. This frees the user from that long water supply hose. The main part of an extractor consists of a clean solution tank, recovery tank, suction motor, cleaning nozzle, some type of solution spraying system and sometimes a motor or turbine driven brush. If a hose is used there will also be a motor or turbine driven pump to force the solution to the end of the hose.
The extractors which look like uprights have the tanks, suction motor, main nozzle, etc. built into one unit. The whole unit is pushed around much like using an upright vacuum cleaner. The solution is typically gravity fed to the spray nozzles right behind the suction nozzle. Most have brushes mounted in the same area to agitate the carpet for better cleaning effectiveness. For cleaning upholstered furniture and carpeted stairs most have a special hose and smaller nozzle with detachable stationary brushes. A sponge type device can be attached to some main nozzles for cleaning non-carpeted floors as well.
The canister type of extractor with separate hose and nozzle has the tanks and suction motor built into a case which is pulled after the user. Just the nozzle at the end of the hose and wands is moved back and forth across the carpet to clean it. Some deluxe units like made by Bissell have a motor drive revolving brush in their nozzle to aid in the cleaning process. These nozzles are a lot lighter to move across the carpet than the upright type extractors. The disadvantage is that they aren't as convenient to set up and store as the self-contained upright type. Having to pull them around behind you can be a nuisance as well. The small portable extractor is a variation of the canister type in a smaller package. While these may seem handy for furniture and stairs, their effectiveness is often rather poor.
Hot water extractors work best when used to periodically clean carpets which are lightly soiled. Performance on a heavily soiled or stained carpet can be disappointing at best. For more heavy duty cleaning needs, look to the professional carpet cleaning services in your area. Their heavy duty commercial equipment is much more powerful and able to produce more satisfactory results.
The traditional carpet shampooer as well as special machines which work a powder or cleaning compound into the carpet to clean its fibers all can be classified as carpet scrubbers. The main distinction of these machines is that they apply a solution or compound to the carpets, scrubbing them in the cleaning process but they do not remove the residue from the carpets. After the carpet dries, an vacuum cleaner with a revolving brush is used to remove the residue and soil.
The shampooer creates a foam from a water and shampoo solution and applies it to the carpet while working the fibers with revolving or rotating brushes. Shampooers are better at cutting greasier or heavily soiled carpets than the typical hot water extractor. While most are separate machines designed primarily for this use, one company, Kirby, makes a shampooer which is an attachment for their upright. It creates a very dry foam (little water content) which cleans well while yielding a reduced drying time. I wouldn't recommend buying such a high priced upright just for the purpose of getting a good shampooer but if you have one, I recommend that you use it.
The scrubbers that work a dry or slightly moist cleaning compound into the carpet fibers work well and require very little drying time. They are often safer for the carpet backing and mat since they do not have the risk of getting them wet like what can happen when a hot water extractor and shampooer is improperly used. While most are separate machines designed specifically for the compound being used, one company, Lindhaus, has a special nozzle for their two-motor upright vacuum cleaner which is designed to work with their cleaning compound. The Host "Dry" Carpet Cleaning System is a popular rental unit which has been top rated by a leading consumer magazine.
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