The Science of Carpet Cleaning

Carpet Cleaning Methods 101

There are two types of carpet cleaning: Low Moisture (or “Dry Cleaning”) and Hot Water Extraction (or “Steam Cleaning”).

Low Moisture or Dry Cleaning Methods:

Within the family of so-called dry cleaning methods for carpets, there are three types of systems used by professionals. Actually, the term “dry cleaning” is a misnomer.

  • Dry cleaning usually refers to a process using a waterless liquid to clean fabrics such as clothing or draperies.
  • These solvents are petroleum products similar to paint thinner; some are harmful to breathe.
  • Using dry cleaning solvents to clean carpets is dangerous and could cause damage to your carpets, so true “dry cleaning” products are never used to clean carpets.
  • In fact, ALL carpet cleaning systems use water: it’s just that some use less water than others.
  • When the term “dry cleaning” is used, it really means LOW MOISTURE carpet cleaning systems that remove soil by absorption or transference.
  • The benefits of low moisture cleaning include fast production, fast dry times, and low cost.
  • The drawback to low moisture systems is that they offer no rinsing to remove detergent residues and soil.

Dry Cleaning Processes:

  • Dry foam: The carpet cleaner applies a liquid foam crystallizing shampoo to your carpet, allows it to dry, and then, without rinsing, removes the dried shampoo into a vacuum. Only the most expensive shampoos actually crystallize; most leave a sticky residue behind. Dry Foam is an effective method as an interim cleaning process, and it can be used prior to hot water extraction cleaning in restorative situations, to suspend soil. It is not a cleaning process by itself.
  • Absorbent pad (bonnet cleaning): This method is similar to dry foam, except that the technician sets a large cotton bonnet on your carpet. The rotating motion causes the bonnet to absorb dirt from your carpet. Bonnet cleaning is like trying to use a large cotton towel or mop to rub the dirt out of your carpet. There’s no rinsing or flushing process. If the bonnet isn’t changed out with a clean one frequently enough, it just smears soil around the carpet. Again, it’s fine for maintenance cleaning, but it is not a restorative process.
  • Dry, absorbent powder: The dry-compound method spreads a moist, absorbent powder throughout your carpet. The powder is allowed to dry and is then sucked into a vacuum. This method leaves dry sponge particles at the base of the carpet yarn. Because the carpet is not rinsed, this is also not a restorative method.

Hot Water Extraction or Steam Cleaning Methods:

Hot water extraction, sometimes called “steam cleaning,” is the second type of carpet cleaning. It is a fancy way of saying that a hot-water cleaning solution is sprayed into your carpet fibers and then removed quickly with a powerful vacuum system.

  • Recommended by all carpet manufacturers: In a recent technical bulletin, Shaw Industries, the world’s largest carpet manufacturer, “recommends the high volume hot-water extraction system, which research indicates provides the best capability for cleaning.”
  • Removes contaminants: No question, the most effective way to clean carpeting is with hot-water extraction equipment. It’s the most powerful cleaning equipment on the market; it’s the only equipment that cleans your carpet of dirt, harmful bacteria, fungi, chemicals, pollens, and tobacco residue.
  • Safe, healthy process: Some people believe that hot water damages your carpet, but this isn’t true. By washing and then rinsing your carpet with hot water, we clean your carpet completely, in the same way that a person who showers and then rinses off the dirt and soap will be much cleaner than a person who takes only a sponge bath.

Professionals who use hot water extraction systems use either portable or truck-mounted equipment. Truck-mounted equipment offers the best results because of tremendous heat, water pressure, and incredible vacuum strength that recovers up to 95% of the water used in the cleaning process. Portable units have the advantage of going where truck-mounted systems cannot-into high-rise apartments and office buildings.

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