Basically, carpet cleaning methods can be placed in one of two categories: Wet or Dry Cleaning. Wet cleaning involves using cleaning solution and hot water extraction. Dry cleaning involves the use of chemicals applied by a rotating pad or brush.
Lets take a closer look at these two methods:
Hot Water Extraction or Steam Cleaning
This method is also known as restorative cleaning. That's because its the only carpet cleaning method known to remove 97% of the dirt and bacteria from carpet. It is also the only method that reaches all the way down to the base of the pile, to give the carpet a thorough clean.
The smallest portable machine rented at a supermarket could be called a 'steam cleaner', but a powerful truck mounted machine is obviously more capable of doing a thorough and effective cleaning job. A trained carpet cleaning technician will know what pressure to use, what cleaning products to use and how to get the maximum soil and stain removal without over-wetting the carpet or leaving a sticky residue behind.
As stated the hot water extraction method can reach down deep into the pile to remove anything that has seeped to the base of the pile, which is then flushed out.
With a truck mounted machine that has powerful suction capabilities, the drying time is reduced and can be sped up with the use of drying equipment, if time is short.
This method is an interim cleaning and involves the use of chemical to clean the carpet fibres. A chemical solution is applied to the carpet and left for a suitable dwell or reaction time. A rotoray machine fitted with an absorbent pad, similar to a towel, or brush, spins across the surface of the carpet, absorbing the soil.
Because this method only works on the top layers of the carpet, it is almost completely ineffective for treating deep soiling and stains, and should only be used for light cleaning. There is also a tendency for some residue to be left behind in the carpet, exposing the occupants to the residue. If you use this option, make sure you fully understand what chemicals are being used.
For those who are concerned about chemical exposure, hot water extracted would be a better option.