Common sense may tell you that the various cleaning methods known collectively as low-moisture cleaning involve minimal amounts of moisture. And as long as there are carpets to clean it is a good bet that debates on moisture and cleaning methodology will maintain a steady presence on industry Bulletin Boards, at trade shows and in the pages of trade publications. Those debates, as entertaining and informative as they can be, will for now be left to others as we take a quick look at five methods of low-moisture cleaning, hopefully shedding some light on the processes for those unfamiliar with them.

The shampoo cleaning method can be thought of - though it is a bit of a stretch - as shampooing your hair without the shower. A shampoo is distributed to the carpet (hair), agitated with a mechanical brush (fingers), then extracted along with suspended soil by either a wet vacuum or through dry vacuuming.

When a non-foaming detergent is applied with a sprayer, agitation is accomplished with counter-rotating cylindrical brushes. Application through the shower or channel-fed brush is accompanied with uniform shampoo distribution using rotating brush action. Once the application and agitation are complete, the suspended soil is extracted along with the excess shampoo with wet vacuuming. Additional soil extraction is accomplished once the carpet is dry, and the remaining (and now dry) detergent residues are removed with dry vacuuming.

Dry-foam cleaning involves producing and distributing a dense foam to the carpet via a mechanical brush. The excess foam and suspended soil is then extracted using a wet vacuum that is typically incorporated into the same machine.

Dry foam begins life as a cleaning agent introduced into the machine. The properly diluted solution is aerated with mechanical agitation into this dense foam. Agitation, usually accomplished by rotary or cylindrical brushes, may take place during or immediately after the application of the foam. Once the appropriate dwell time has elapsed, the technician, using a wet vac, extracts the excess foam and suspended soils.

The mist-and-brush method works by agitating a non-foaming detergent into the carpet with a mechanical brush. Once dry, the carpet is dry-vacuumed and the detergent and suspended soil is removed.

The detergent is applied with a sprayer, after which a machine with counter-rotating cylindrical brushes is brought to bear. The carpet yarns are lifted up evenly, and the soils are suspended for removal by dry vacuuming.

The bonnet cleaning method, sometimes referred to as the absorbent pad method, is a low-moisture method in which a detergent solution is applied to the carpet, then extracted with a bonnet/absorbent pad attached to the drive block of a low-rpm rotary floor machine.

The drive block transmits a rotating motion to the bonnet, which is made of cotton, rayon or a combination of the two. During the agitation phase of soil extraction, the bonnet absorbs suspended soils. The rate of absorption needs to be monitored; once the bonnet accumulates a significant amount of soil, it must be either turned over or replaced (obviously, once both sides of the pad are soil-saturated, it is time for a fresh pad). When the carpet dries, dry vacuuming can result in further soil extraction as remaining detergents are extracted from the carpet.

The absorbent compound method uses a granular carrier. Once the carrier is uniformly distributed and dried it is removed, along with the suspended soils, through dry vacuuming.

The chemical action is accomplished using an absorbent compound (hence the name) consisting of a cellulose- or polymer-based carrier. The compound is mixed with an anionic or nonionic detergent with a pH range of 5 to 10. Application rates and dispersion methods vary.

The compound's temperature will approximate that of the ambient air in the room being cleaned. Distribution is generally accomplished with equipment incorporating two counter-rotating brushes, rotary-brush action or hand pile-brushing action.

Low-moisture cleaning continues to gain in both popularity and prestige. Those professionals looking to expand their cleaning repertoire might do well to investigate the various low-moisture methods available for them to add to their arsenal.