Carpet cleaning methods, an overview.
When specifying and purchasing carpet it is important to balance aesthetic consideration with performance and maintenance requirements. A carpet should
be selected that is both aesthetically appealing and capable of meeting the demands of time and traffic.
The selection of a carpet maintenance program should begin with a working understanding of the available today including their capabilities and
limitations. The professional cleaner is in a unique position to influence the consumer regarding carpeting: therefore, it should be understood by the dealer and the consumer that the equipment, chemicals,
techniques, and operator must be the best possible to be an effective cleaning system. Justifying price or the use of "here today gone tomorrow" companies often results in disillusioned customers and
costly claims for the dealer and the manufacturer.
Listed below is a brief overview of the most commonly used cleaning methods available today:
Cylindrical Foam Shampoo.
This method uses an air compressor which "whips" the shampoo solution into a heavy foam. This foam is then brushed into the carpet using a mechanically driven cylindrical brush composed of nylon bristles. A catch pan attached
to the unit captures the soil burdened shampoo. The carpet is then vacuumed, theoretically removing any remaining cleaning residues. Recovery rate of the expended solution is approximately 15 percent.
Drying time is typically 4 to 6 hours. This method is totally inadequate for heavy soil and often relies on chemicals containing high amounts of optical brighteners The brightener is normally a mild chlorine bleach
solution which can permanently discolor nylons.
Rotary Brush Method.
Basically uses the same foam cleaning chemicals as the cylindrical foam shampoo method. This machine has an attached tank for the diluted shampoo solution with a tube leading into a shower fed round brush composed of nylon, polypropylene or natural bristles. The shampoo solution drips onto the carpet where it is scrubbed, creating the foam. The revolving brush agitates the soil loose from the fiber. The encapsulated soil and cleaning residue is then vacuumed up. Drying time is 4 to 10 hours, depending upon the operator. The problem with this method is it uses sodium lauryl sulfate, which leaves a very sticky, soil attracting residue. Overwetting and pile distortion are other commonly associated drawbacks. The recovery rate of this system is generally 10 percent of the expended solution but can be increased up to 75 percent when rinse and extraction equipment is coupled with the unit. ( truck mount extraction versus a local unit as typical with those available to rent ).
Bonnet/Spin Pad Method.
This method is similar to the rotary method, and the machine used is essentially the same. A solution of detergent and water is sprayed on the carpet. A rotating, absorbent pad generally made of cotton or abrasive olefin strips
agitates the carpet pile. In theory the pad absorbs the cleaning solution plus the suspended soil. Although this method offers less pile distortion, less residue and less drying time than the rotary
shampoo method, most of the soil is buried in rather than removed from the carpet. Recovery rate of the expended solution is approximately 10 percent; therefore, this system rates the poorest in this category.
Furthermore, the mechanical action of this cleaning method can cause abrasive soils to damage the carpet fibers. Fiber distortion is also a concern if the drive brush hits the carpet. This method is not for cut
piles or berbers. Drying time is 4 to 10 hours. Unfortunately this machine is commonly used in commercial carpet cleaning since it requires little operator training and is generally kept on site for hard floor
maintenance. Rapid resoling due to cleaning residue is common.
Dry Extraction Powders.
This method relies on "dry" granular sponges made of either organic or mineral materials. The organic type, which are yellow in color, can contain sawdust, ground up corn and corn stalks or other plant materials. The mineral types are very fine white sponges that contain water, solvents, detergents, and optical brighteners. These sponges are brushed into the carpet by hand or mechanical action where they dwell for a short period of time. During the dwell phase these sponges absorb soils. When the sponge dries it is then vacuumed out of the carpet. This method is effective for most soils and is easy to use. The disadvantages of this method include the use of chlorinated solvent pre-sprays on heavily soiled carpet and total reliance on the effectiveness of the vacuum cleaner to remove the sponges from the carpet. Two final concerns are the unrecovered mineral types can cake up and become a food source for dust mites and the unrecovered mineral types can cake up and become even more difficult to remove if they become wet.
Hot Water Extraction.
This method is commonly referred to as "steam" cleaning although water vapor instead of live steam (which requires temperatures in excess of 240 degrees Fahrenheit ) is employed. This method relies on a truck mounted or portable base unit that supplies a fine mist of water and detergent applied using pressure from a nozzle fed floor tool. The floor tool is also equipped with an extraction (vacuum) apparatus that passes over and removes the sprayed solution immediately after it is applied. The advantages of this method is its high degree of flexibility and control during operation. Typically recovery of the expended solution is 90 percent; however, high velocity systems can attain up to 95 to 97 percent recovery with drying time as little as 4 hours. From the stand point of indoor air quality, external extraction
systems exhaust all moisture and biological residue outside the environment. All of these characteristics makes the hot water extraction system perhaps the most complete method of cleaning when properly
applied. Although this system offers controls over the depth of cleaning, high end output can lead to over wetting, longer drying time, wicking and delamination.
The key to adequate carpet cleaning is to remove dirt without damage to the carpet or the carpet fibers. The only way this can be done is with
knowledge and controls; knowledge about the carpet to be cleaned, the effects of the various cleaning methods available and the controls over the detergents, spotters, or solvents used.
cleaning overview courtesy of Beaulieu Carpets technical services department.
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