At this point the chemical is whipped into a foam and worked into the carpet with the rotating brush. The other type of machine is more commonly referred to as a dry foam or Dry Foam Extraction Machine. This machine uses the same chemical but rather than a large brush sitting directly on the carpet, it has a cylinder brush to work the foam and agitate the carpet. As with the absorbent pad method , shampoo and dry foam cleaning is fast and does not require extensive training for the technician. When the procedure is done correctly, the dry foam will impart only a small amount of moisture thus leaving the carpet to dry in 2 to 4 hours.
Excellent agitation is achieved through the aggressive brush action of the machine.
Combine the agitation with a good chemical action achieved by the lubrication and suspension of shampoo and you have good soil release from the fiber. While an extraction process is sometimes included with this system, thorough soil removal is not achieved as compared to hot water extraction . Temperature being an important fundamental of cleaning is a negative feature of this method. Under the very best circumstances, only luke warm foam will come in contact with the carpet. Overwetting is another strong possibility if the technician is untrained and the equipment malfunctions.