to the more thorough cleaning methods accepted in the industry. Vacuum 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 but don't necessarily improve the machines ability to remove dirt from the surface being cleaned. Modern carpet cleaning equipment use rotary vacuum heads and spray jets to deep clean the carpet through hundreds of multi-directional cleaning passes. Some add steam and agitation. Models include upright (dirty-air and clean-air), canister and backpack, wet-dry and pneumatic, and other varieties. Robotic vacuum cleaners have recently become available. Stain removal 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 used 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. 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. Other Carpet rods, rattan rugbeaters, carpet-beating machines, brooms, brushes, dustpans, and shaking and hanging were all carpet-cleaning methods of the 19th century; brooms particularly carry risks of wear. References Rugs and carpets Floors Cleaning