This is one of the oldest carpet cleaning methods around. It is still very effective but is not commonly used although it is gaining popularity once again.
The most common piece of equipment used for this process is a rotary floor machine. The machine spins at either 175 or 300 revolutions per minute. Attached to the bottom of the machine will be a soft bristle brush usually made of nylon.
The carpet cleaner will either spray the carpet with a solution or use a tank mounted on the machine to automatically apply the product. The shampoo used is specially designed to lightly foam and trap soil. The machine agitates the solution picking up and trapping the soil. The shampoo is left to dry in the carpet where it will form a brittle crystalline residue and is later vacuumed out along with the absorbed soil. This process received many negative responses in the past because of soil attracting residue left in the carpet but today’s modern chemicals leave little if any residue behind to attract soil. This process is rarely used in residential settings and is mainly a commercial cleaning process.
It usually takes the carpet between 1 to 2 hours for carpet to be dry to the touch after this process. The shampoo may take up to 24 hours to fully crystalize however so it is usually not vacuumed until the next day.
This process can also be called “Encapsulation.” Instead of a rotary floor machine the company may use a cylindrical brush machine or a number of other machines for agitation