Low-moisture cleaning is a broad umbrella encompassing a selection of carpet-cleaning methods involving minimal amounts of moisture. While it is a safe bet that debates on moisture and cleaning methodology will continue for as long as there are carpets to clean, they will be left, for now, to the soapboxes of others; this is a brief examination of five methods of low-moisture cleaning that should shed some light on the concept for those unfamiliar with it.

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 rotating motions 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, as 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, further soil extraction may be accomplished as remaining detergents are extracted from the carpet through dry vacuuming.

Dry foam cleaning is just that: a dense foam is produced and distributed to the carpet via a mechanical brush. 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 a 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, a wet vac extracts the excess foam and suspended soils.

The shampoo cleaning method can be thought of (albeit with some stretching) 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 application and agitation are complete, suspended soil is extracted, along with the excess shampoo, with wet vacuuming. Further soil extraction is accomplished once the carpet is dry and the remaining detergent residues, now dry as well, are removed with dry vacuuming.

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 featuring counter-rotating cylindrical brushes is brought to bear. The carpet yarns are lifted up evenly, and the soils are suspended for later removal by dry vacuuming.

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. The compound remains in the carpet until dry, at which time it is extracted through dry vacuuming.