Low Moisture Carpet Care

April 2, 2013

While the term is quite familiar and understood by many in the carpet cleaning industry, building owners and managers may be less familiar with what “low moisture” carpet cleaning is all about.  It refers to any method, procedure, or form of carpet cleaning that allows carpet fibers to dry and return to their natural state in two hours or less at approximately 65% humidity and at 70 degrees (F).

The goal is to reduce the amount of moisture applied or remains in the carpet during and after the carpet cleaning process so that it dries quickly and evenly.  This helps protect the carpet, its backing, and the subfloor below the carpet.  It also helps eliminate possible saturation of the carpet, which can result in mold, mildew, bacteria, or other contaminants developing.

According to Mark Warner of the Low Moisture Carpet Cleaning Association, the use of low moisture carpet cleaning equipment and techniques can also increase the carpet’s performance and appearance.  “It can also extend the useful life of the carpet, enhance the ability to service the carpet, and minimize downtime waiting for ‘just cleaned’ carpeted areas to dry, which is a major consideration in a commercial office building or similar facility,” he says.

However, in some situations, drying carpets in two hours or less can be difficult.  Every facility has its own environmental and climatic conditions that can impact drying times.  And, some carpets are more heavily soiled than others or contain specific types of soils (e.g., grease, oil, certain types of food spills, etc.), which may require the use of additional water and cleaning solution, and other measures to effectively remove these contaminants.  Because of this, different carpet cleaning methods may have to be employed to meet the goals of low moisture cleaning.

Some of these methods include the following:

Bonnet cleaning: With this system, a cleaning product is applied to the carpet and then extracted with an absorbent bonnet attached to a low-rpm (rotations per minute) floor machine.  The floor machine provide agitation to help loosen and remove soils and it can accumulate a significant amount of soil in the process.  For this reason, the bonnet may need to be turned over or replaced frequently during the cleaning process.  Once the carpets are dry, vacuuming is often recommended to remove any remaining cleaning chemicals or soil in the carpet.

Shampoo cleaning: In many ways, this is similar to bonnet cleaning.  A low rpm floor machine distributes a specially-formulated liquid detergent onto the carpet.  This method also agitates the carpet to help loosen and remove soils.  Once this step is complete, what is referred to as suspended soil is extracted, along with the shampoo and moisture, using a wet vacuuming system.  Then, once the carpet has sufficiently dried, vacuuming is performed to remove any remaining soils or shampoo/detergent residue.

Encapsulation: With this method, encapsulation chemicals are applied to carpet using a low-rpm floor machine or a cylindrical machine that has brushes, instead of pads, to work chemicals into the carpet.  Once in the carpet, these chemicals crystallize.  This takes about 30 minutes to an hour.  Then, the carpets are vacuumed, removing the crystals and soils.  This method typically requires no water at all.

There are several additional low moisture processes that could be mentioned, including: other dry methods that also require no water; dry foam; and a mist-and-brush method that uses a non-foaming detergent and a floor machine or similar equipment.  While all of these techniques can be used to meet the goals of low moisture carpet cleaning, they also may pose potential problems.

For instance, with bonnet and shampoo cleaning, some chemical residue may be left in the carpet after cleaning.  In many cases, this can lead to what is called “rapid re-soiling,” where the residue actually attracts more soils.  Additionally, one somewhat controversial element of a carpet shampoo detergent is that it may include an optical brightener.  While the brightener can improve the carpet’s appearance after cleaning, over time it can negatively impact its color of the carpet.  Moreover, depending on what types of encapsulation chemicals are used, re-soiling can be an issue with this method as well.PageBreak

However, the big concern with all of these methods is that most carpet cleaning professionals agree they do not “deep clean” carpets.  They can help remove surface level soils and, as a result, they are typically viewed as interim carpet cleaning methods, providing “temporary” carpet care.  In some cases, facilities use these cleaning practices as a stop gap measure to clean carpets until a more thorough carpet cleaning can be performed.  More thorough cleaning usually involves the use of a hot-water carpet extractor and fortunately, some manufacturers are now making low moisture carpet extractors.

Low Moisture Carpet Extractors

Along with a cleaning solution/chemical that is often sprayed onto the carpet as the first step in the carpet cleaning process, hot-water carpet extractors use a combination of heat, pressure, and suction to remove soils from carpet fibers.  This method is designed to deep clean carpets, unlike some other methods discussed earlier that typically remove just surface level soils.  In most cases, an effective carpet extractor allows the cleaning solution to penetrate even the deepest areas of the carpet to help suspend soils, which are then extracted by the machine.

Many early carpet extractors used considerable amounts of water—typically, 1.5 gallons per minute, if not more.  By comparison, most low moisture systems use one gallon of water or less.  In some cases, this is enough to clean at least 300 square feet of carpeting.  Not only is less water applied to the carpet using a low moisture machine, but the process can also help reduce the amount of wastewater generated, potentially reducing carpet cleaning’s overall impact on the environment.


Further, low moisture systems usually have much more powerful vacuum motors than conventional or earlier extractors, helping to more effectively remove moisture from the carpet and speed drying.  Even new wand technologies can help improve moisture recovery. 

While it is not always necessary to speed the drying process when using low moisture carpet extractors, commercial air movers (blowers) can be installed strategically around the just cleaning carpeted area.  Installed directly over the carpet, and not pointed on the carpet, air movers can cut drying times in half.

Some in the professional carpet cleaning industry view low moisture cleaning as a “Greener” way to clean carpets because less moisture and possibly less chemical is used.  However, for building professionals, low moisture equipment and procedures are most appreciated for providing quicker drying times, allowing cleaned areas to be open in a timely fashion, maintaining and not hindering a carpet’s appearance and function, and having deep cleaning capabilities when using a hot-water extractor.  While the term low moisture may be foreign to some in the buildings industries, its impact is clearly significant for the future of the carpet care industry.


Mark Cuddy is the national sales manager for U.S. Products.

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Mark Cuddy