Successful soil removal depends on these four fundamentals: Temperature (heat), Agitation, Chemical action and Time. The acronym TACT helps us remember the four fundamentals for suspending soils:
Temperature/Heat. The speed of chemical reactions doubles for every 20° F (11°C) increase in temperature. The efficiency of a carpet cleaning procedure is dependent on the temperature of the water used in the process, thus “hot water extraction.” (Hot water extraction is not the same process as steam cleaning. Steam cleaning procedures are used in many industrial procedures but typically not in carpet cleaning.)
Agitation. Every type of soil has to be physically picked up, brushed away or rinsed off the surface of the carpet fiber. Various means of agitation exist to remove soils, such as brushes, streams of water and air, and absorbents (e.g., towels or bonnets). As agitation increases, so does the rate of soil removal. There is a practical limit, of course. Too much friction and pressure will damage the surface. Agitation also helps to distribute cleaning agents, such as preconditioners, through the carpet fibers.
Chemical action. The primary role of chemicals is to attack soils with the goal of loosening, dissolving and separating them from the carpet fibers, then suspending them in the chemical solution for extraction.
Time. No matter how hot the water, how aggressive the agitation or how effective the detergent, adequate dwell time is required for a cleaning solution, such as a preconditioner or spotting agent, to suspend soils. Consider something as simple as a spill of sugar water on a carpet. The sugar dries to a thick, syrupy liquid. It takes time to dissolve this liquid. Follow product instructions carefully to ensure you're allowing adequate dwell time.
The more we apply these four principles, the more effective our cleaning procedures and the better the cleaning outcomes.
When it doesn't work as planned, you can use one of the four to compensate for another. For example, if you cannot apply the chemical strength that you want because the fiber cannot tolerate high pH, or you might damage the surface with too much agitation, you have to use one or more of the other elements to compensate. Higher temperature, for example, can sometimes compensate for lack of dwell time or agitation.