"Shaw Industries recommends the hot water extraction system, which research indicates provides the best capability for cleaning. This system is commonly referred to as "steam cleaning," although no steam is actually generated. The 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. This can be done from a truck-mounted unit outside the home with only the hose and wand brought inside or, where a truck-mounted unit cannot reach, by a portable, self-contained system brought into the home.
Bonnet cleaning systems (commonly known as Chem-Dry™) employ a rotating bonnet of terry cloth or other absorbent material to agitate the carpet pile and absorb soil. A detergent solution is sprayed onto the pile and then worked with the bonnet attached to a rotary floor polisher.
NOTE: Shaw Industries does not recommend this cleaning system. The bonnet system 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."