Carpet cleaning, for beautification, and the removal of stains, dirt, grit, sand, and allergens can be achieved by several methods, both traditional and modern. Clean carpets are recognized by manufacturers as being more visually pleasing, potentially longer-lasting, and probably healthier than poorly maintained carpets. Sanitary Maintenance magazine reports that carpet cleaning is widely misunderstood, and chemical developers have only within recent decades created new carpet-care technologies. Particularly, encapsulation and other green technologies work better, are easier to use, require less training, save more time and money, and lead to less resoiling than prior methods.
Hot water extraction vs steam cleaning
Although there is an industrial cleaning process that is in fact steam cleaning, in the context of carpet cleaning, "steam cleaning" is usually a misnomer for or mischaracterization of the hot water extraction cleaning method. The hot water extraction cleaning method uses equipment that sprays heated water (not steam), sometimes with added cleaning chemicals, on the carpet while simultaneously vacuuming the sprayed water along with any dislodged and dissolved dirt. Many carpet manufacturers recommend professional hot water extraction as the most effective carpet cleaning method. Actual steam could damage manmade carpet fibers or shrink natural fibers such as wool.
The primary advantage of the hot water extraction cleaning method is that effective cleaning is possible using only hot water, or hot water with very dilute detergent solutions. This avoids the problems associated with detergent residues that can remain in the carpet with other cleaning methods. Detergent residues on carpet fibers can attract dirt from the soles of shoes as people walk on a carpet, causing the carpet to become dirty again soon after cleaning.
Since the use of detergents and other chemicals is minimized or avoided altogether with the hot water extraction cleaning method, this method is advantageous for persons concerned about possible chemical exposure, especially for children crawling or playing on recently cleaned carpets. This method also minimizes concerns about breathing volatile chemical compounds that might be used in other cleaning methods.
The primary disadvantage of the hot water extraction cleaning method is that 100% of the water used cannot be removed. If poor water extraction is achieved, in conditions of high humidity, mold growth could occur or be exacerbated. This is not usually a problem with high end commercial water extraction equipment. Moisture left in carpets after cleaning will evaporate more quickly with ventilation, heating, air conditioning or dehumidification.
A variety of hot water extraction carpet cleaning equipment is available, with less expensive equipment marketed for purchase or rental by homeowners, and more expensive equipment used by professional carpet cleaners. The more expensive commercial equipment may employ a rotating high pressure spray and extraction disc. This allows the equipment to achieve many spray-extraction cycles independent of the forward or backward motion of the machine.
Hot water extraction carpet cleaning equipment may be a portable unit that plugs into an electrical outlet or a truck mount carpet cleaner requiring long hoses going from the truck or trailer to the room requiring cleaning. Truck mounted equipment is advantageous where electricity is unavailable (e.g. for cleaning premises where the electrical service was terminated when the premises were vacated by a departing tenant.) Truck mount carpet cleaning may be unsuited to premises distant from a driveway or road, and hoses may need to pass through windows to reach upper floors of a building. Hoses needed for truck mount and professional portable carpet cleaning may present an inconvenience or tripping hazard to users of hallways, and pets or children can escape through doors that must be left ajar for hoses. Heated or air conditioned air will also escape from buildings when doors are left open for hoses. This could create a significant waste of energy in some climates. While truck mounted carpet cleaning equipment minimizes noise in the room being cleaned, truck mounted carpet cleaning equipment may cause noise and air pollution offensive to neighbors and may violate anti-idling bylaws in some jurisdictions. However truckmounted cleaning is much faster than portable equipment and extra heat and power can give better results and faster drying times.
In high-pressure hot water extraction ("steam cleaning"), after preconditioning, with alkaline agents such as ammonia solution for synthetic carpets or acidic solution (such as vinegar solution) for woolen carpets, and agitation with a grooming brush or an automatic scrubbing machine, a pressurized manual or automatic cleaning tool (such as a wand) passes over the surface several times to thoroughly rinse out all preconditioner, residue, and particulates. If an alkaline detergent is used on a woolen fibre, use of an acetic acid solution will restore neutral fiber pH. The acid rinse thus neutralizes the alkaline residues, and can contribute to softening cleaned fabrics.
The steam-cleaning system uses detergent-based solutions. The surface is saturated, typically taking 12–24 hours to dry. Some carpet-cleaning solutions are carbonated to dissolve organic material more effectively. Beyond these treatments, antistaining and antisoiling products can be applied by the carpet owner, and have for this reason become recognized in the carpet-cleaning industry as some of its biggest profit centers.
Extraction is by far the most important step in this process. Since the hot-water extraction method uses much more water than other methods like bonnet or shampoo cleaning, proper extraction and air flow are critical to avoid drying issues. 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 has led to customer fears and concerns about very slow drying, the risk of discoloration returning during drying, and odors, bacteria, fungi, molds, and mildews. Balancing the need for 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) is a key technique that must be mastered by carpet-cleaning technicians.
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.
Many dry carpet-cleaning systems rely on specialized machines; dry carpet-cleaning machines include those manufactured by Brush and Clean, Host Dry, and Whittaker System. These systems are mostly technically "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, or of pretreatments, preconditioners, or "traffic-lane cleaners", which are detergents or emulsifiers that break the binding of different soils to carpet fibers over a short period of time, commonly sprayed onto carpet prior to the primary use of the dry-cleaning system. One chemical dissolves the greasy films that bind soils and prevent effective soil removal by 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.
A 98% biodegradable 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; dirt and grime is attracted to the compound, which is then vacuumed off, leaving carpet immediately clean and dry. 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.
In the 1990s, new polymers began literally encapsulating (crystallizing) soil particles into dry residues on contact, in a process now regarded by the industry as a growing, up-and-coming technology; working like "tiny sponges", the deep-cleaning compound crystals dissolve and absorb dirt prior to its removal from the carpet. Cleaning solution is applied by rotary machine, brush applicator, or compression sprayer. Dry residue is vacuumable immediately, 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 vacuumed (as opposed to the dry powder 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.
After club soda mixed with cleaning product is deposited onto the surface as mist, a round buffer or "bonnet" scrubs the mixture with rotating motion. This industry machine resembles a floor buffer, with an absorbent spin pad that attracts soil and is rinsed or replaced repeatedly. The bonnet method is not strictly dry-cleaning and involves significant drying time. To reduce pile distortion, the absorbent pad should be kept well-lubricated with cleaning solution.
When there is a large amount of foreign material below the carpet backing, extraction with a wet process may be needed. The spin-bonnet method may not be as capable of sanitizing carpet fibers due to the lack of hot water, but a post-cleaning application of an antimicrobial agent is used to make up for this. Compared to steam cleaning, the small amounts of water required with spin-bonnet carpet cleaning favor water-conservation considerations.
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. Wet shampoos were once formulated from coconut oil soaps; wet shampoo residues can be foamy or sticky, and steam cleaning often reveals dirt unextracted by shampoos. Since no rinse is performed, the powerful residue can continue to collect dirt after cleaning, leading to the misconception that carpet cleaning can lead to the carpet getting "dirtier faster" after the cleaning.
When wet-shampoo chemistry standards converted from coconut oil soaps to synthetic detergents as a base, the shampoos dried to a powder, and loosened dirt would attach to the powder components, requiring vacuuming by the consumer the day after cleaning.
Dry Foam Carpet Cleaning
The dry foam cleaning on carpets is done by the dry foam machine. Even though the name implies it, it does not involve complete dryness as it does have low moisture that is 90% air and 10% liquid. The dry foam machine consists of a pressure tank in which a solution of water and shampoo is added.
Other household carpet-cleaning processes are much older than industry standardization, and have varying degrees of effectiveness as supplements to the more thorough cleaning methods accepted in the industry.
Vacuum cleaners use air pumps to create partial vacuums to suck up dust and dirt, usually from floors and carpets. Filtering systems or cyclones collect dirt for later disposal. Models include upright (dirty-air and clean-air), canister and backpack, wet-dry and pneumatic, and other varieties. Robotic vacuum cleaners have recently become viable as well.
Frequent vacuuming prolongs the life of your carpet by preventing a buildup of gritty particles that can cut carpet fibers. Every few weeks, take a little extra time and use your crevice tool for cleaning around baseboards and radiators and in other hard-to-reach places; 
Vacuum-cleaner manufacturers are widespread and include Aerus LLC, Bissell, Black & Decker DustBuster, Dirt Devil, Dyson, Electrolux, Eureka, Goblin Vacuum Cleaners, Hoover, Kenmore, the Kirby Company, Miele, Nilfisk-Advance, Numatic International Limited, Oreck, Regina, Rexair LLC, Samsung Electronics
Tea leaves and cut grass were formerly common for floor cleaning, to collect dust from carpets, albeit with risks of stains. Ink was removed with lemon or with oxalic acid and hartshorn; oil with white bread or with pipe clay; grease fats with turpentine; ox gall and naphtha were also general cleaners. Ammonia and chloroform were recommended for acid discoloration. Benzine and alum were suggested for removing insects; diatomaceous earth and material similar to cat litter are still common for removing infestations. Candle wax is removed by placing a towel over the affected carpet area and applying steam from a clothes iron until the wax absorbs into the towel. Some traditional methods of stain removal remain successful and ecological. Caution should be addressed when treating natural fibers such as wool.
The longer the stain material remains in the carpet, the higher the chance of permanent color change, even if all the original stain material is removed. At times pets urinate on the carpet and this results in a bad odor especially when it is hot and humid.The carpet or rug is usually taken outside and immersed in water to remove such stains. Immediately blotting (not rubbing) the stain material as soon as possible will help reduce the chances of permanent color change. Artificial food coloring stains are generally considered permanent stains (Kool-Aid, Gatorade, Listerine, soda, etc.). These may be removed by professional cleaners or deep cleaning rental machines with heat-transfer stain-reducing chemicals, but carry risks of burning the carpet. Stain removal products can be combined with anti-allergen treatments to kill house dust mites.
Carpet rods, rattan rugbeaters, and carpet-beating machines for beating out dust, and also brooms, brushes, dustpans, and shaking and hanging were all carpet-cleaning methods of the 19th century; brooms particularly carry risks of wear. Steam Cleaning increases the lifespan of your carpet.
Robert Wittkamp (1942–2007), IICRC-certified master Carpet Cleaners technician with 30 years' expertise in carpet cleaning, commented that old wives' tales persist and thrive within the industry. For instance, the concept that walking barefoot on a carpet may lead to damage from body oils has not been supported or disproven by standardized reports or testing or by industry evidence.
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