Steam Cleaning is sometimes referred to as Hot Water Extraction. In this method, hot cleaning solution is sprayed under pressure onto the carpet and is immediately extracted with a vacuum source. The dirty solution is collected in a recovery tank and is usually poured into the sanitary waste system. The advantage of this system is that is has the ability to flush out large amounts of soil and contaminants in carpet. It is the most preferred method by all of the major fiber producers, such as Dupont, Monsanto and Allied Signal, as well as the carpet manufacturers like, Shaw, Mohawk, World, and Queen.
Because this method removes more contaminants than the other carpet cleaning methods, hot water extraction is favored by the Environmental Protection Agency (EPA) and is the preferred method of the Institute of Inspection, Cleaning and Restoration Certification (IICRC). It does have the disadvantage of having longer drying times and the possibility of wick up of spots if they are not thoroughly extracted. Most higher quality carpets that have extended appearance and texture retention warranties require this type of cleaning every 18 months in order to retain the warranty coverage.
Dry Extraction is when a dry product (powder or ground corn cobs that have been soaked with a solvent chemical) is broadcast over the area to be cleaned. Then either a circular brush or cylindrical rotating brush is used to force the dry cleaning product in contact with the soil. After the carpet dries, a through vacuuming is required to remove the product and loosened soil. This method has the fastest drying times of all carpet cleaning methods and has the advantage of being able to be walked on almost immediately after cleaning. Dry powder cleaning does a fairly good job of cleaning the top 1/3 of the fiber that is visible if it is not heavily soiled. It does not however remove the heavier soils in the base of the fibers. It's weakness is the extraction cycle. If not vacuumed with a powerful commercial vacuum, large amounts of the cleaning product can remain, and over a period of time build up and cause considerable problems later on.
