Hot water extraction — often called steam cleaning — is the method most manufacturers reference for deep cleaning carpet. Done properly it is a sequence, not a single pass with a machine.
Understanding the sequence makes it easy to tell whether a carpet has been cleaned thoroughly or simply wetted and vacuumed.
The sequence
Each stage prepares the next. Skipping any one of them shows up in the result.
- Inspection and fibre identification, including colourfastness testing
- Thorough dry vacuuming to remove loose, abrasive soil before any moisture is introduced
- Pre-spray applied at the correct dilution and pH for the fibre
- Dwell time, so the chemistry has time to break the bond between soil and fibre
- Agitation to work the solution through the pile evenly
- Rinse extraction with hot water under pressure, recovering the soil and solution
- Grooming and drying with airflow to lift the pile and shorten dry time
Why dwell time matters more than pressure
Chemistry needs time. When pre-spray is extracted immediately, the solution has not finished releasing the soil, and the operator compensates with more passes and more water — which slows drying without improving the result.
Correct dwell time is the difference between removing soil and merely moving it.
Rinse and residue
The rinse stage is where detergent residue is removed. Residue left in the pile is sticky and attracts soil, which is why a poorly rinsed carpet re-soils within days and often looks worse than before.
Thorough extraction also removes most of the moisture, which is the main control on drying time.