Drying time may also be decreased by extra use of fans, air conditioning, and/or outdoor ventilation. Older surfaces, such as double jute-backed carpets and loose rugs with natural foundation yarns, could shrink after a wet treatment, leading to suppositions that wet-cleaning could also remove wrinkles. However, this notion is antiquated and this method could also occasionally tear seams or uproot strips. Newer carpets, such as with synthetic backing and foundation yarns, do not shrink, and they smooth easily; in such carpets, wrinkles indicate an underlying problem, such as adhesive, that may need a certified carpet inspector to determine. Wet-cleaning systems naturally require drying time, which may lead to concerns about very slow drying, the risk of discoloration returning during drying, and odors, bacteria, fungi, molds, and mildews. Carpet cleaning specialists try to find a balance between rapid drying (attributable to lower flow rate through the cleaning jets of a spray system) and the need to remove the most soil (attributable to higher flow rate). Pretreatments similar to those in dry-cleaning and "very low moisture" systems are employed, but require a longer dwell time of 15 to 20 minutes, because of lower amounts of carpet agitation. Ideal pretreatments should rinse easily and leave dry, powdery, or crystalline residue that can be flushed without contributing to re-soiling. Dry-cleaning For more details on this topic, see Dry carpet cleaning. Many dry carpet-cleaning systems rely on specialized machines. These systems are mostly "very low moisture" (VLM) systems, relying on dry compounds complemented by application cleaning solutions, and are growing significantly in market share due in part to their very rapid drying time, a significant factor for 24-hour commercial installations. Dry-cleaning and "very low moisture" systems are also often faster and less labor-intensive than wet-extraction systems. Heavily soiled areas require the application of manual spotting, pretreatments, preconditioners, and/or "traffic-lane cleaners", (commonly sprayed onto carpet prior to the primary use of the dry-cleaning system) which are detergents or emulsifiers which break the binding of different soils to carpet fibers over a short period of time. For example, one chemical may dissolve the greasy films that bind soils to the carpet, and thus prevent effective soil removal through vacuuming. The solution may add a solvent like d-limonene, petroleum byproducts, glycol ethers, or butyl agents. The amount of time the pretreatment dwells in the carpet should be less than 15 minutes, due to the thorough carpet brushing common to these "very low moisture" systems, which provides added agitation to ensure the pretreatment works fully through the carpet. The benefit of dry carpet cleaning, over wet solutions, is that dry chemical compounds don't attract dirt, like dried shampoo. While dry carpet cleaning is more expensive and more time consuming to clean than Bonnet or extraction, dry cleaning formulas put less stress on the carpets themselves. Dry compound This section does not cite any sources. Please help improve this section by adding citations to reliable sources.
Unsourced material may be challenged and removed. (March 2015) (Learn how and when to remove this template message) A 98% biodegradable or others, slightly moist absorbent cleaning compound may be spread evenly over carpet and brushed or scrubbed in. For small areas, a household hand brush can work such a compound into carpet pile; working like "tiny sponges", the attracted cleaning solution dissolve dirt, dirt and grime is attracted/absorbed to the compound, after a short drying time (the cleaning solution which is attracted to the compound must evaporate), it will be removed with a vacuum cleaner, the drier the better, leaving carpet immediately clean and dry. But it's very difficult to remove all residues, the residues can cause allergies and biological compounds may cause discolourations on carpets. For commercial applications, a specially designed cylindrical counter-rotating brushing system is used, without a vacuum cleaner. Machine scrubbing is more typical, in that hand scrubbing generally cleans only the top third of carpet. Encapsulation In the 1990s, new polymers began literally encapsulating (crystallizing) soil particles into dry residues on contact. In the conventional cleaning process surfactant molecules attach themselves to oily soil particles, suspending them (emulsification) so that they can be easily rinsed away. Surfactant (detergent) molecules and emulsified soils which escape being rinsed away, remain in the fibre and continue to attract soiling, causing the condition of the carpet to degenerate; often re-soiling faster than before it was subjected to the cleaning process. Encapsulators are speciality detergent polymers which become part of the detergent system. As drying occurs (20-30 min. drytime), after cleaning, these encapsulators bind the detergent molecules and residual soils in a brittle, crystalline structure. Detergent and soil particles can no longer attract other soils and are easily removed by dry vacuuming. In addition to binding the detergent and soil residues the encapsulation chemistry coats the clean fibre with the same brittle film. This reduces the fibre’s affinity for oily and particulate soils. As this brittle film"breaks away" and more soil is removed, the appearance of the fibre improves as opposed to soiling more rapidly. Products which also employ fluorochemical technology, display dramatically extended anti re-soiling time periods. Cleaning solution is applied by rotary machine, brush applicator, or compression sprayer. Dry residue is vacuumable immediately (20-30 min. drytime), either separately or from a built-in unit of the cleaning-system machine. According to ICS Cleaning Specialist, evidence suggests encapsulation improves carpet appearance, compared to other systems; and it is favorable in terms of high-traffic needs, operator training, equipment expense, and lack of wet residue. Encapsulation carpet cleaning also keeps carpets cleaner for longer periods of time compared to other methods. Encapsulation also avoids the drying time of carpet shampoos, making the carpet immediately available for use. The use of encapsulation to create a crystalline residue that can be immediately (20-30 min. drytime) vacuumed (as opposed to the residue of wet cleaning systems, which generally requires an additional day before vacuuming) is a newer technology that has recently become an accepted method for commercial and residential deep cleaning. Shampoo Wet shampoo cleaning with rotary machines, followed by thorough wet vacuuming, was widespread until about the 1970s, but industry perception of shampoo cleaning changed with the advent of encapsulation. Hot-water extraction, also regarded as preferable, had not been introduced either.