Pressure Washing

Pressure Washing - Pressure washing equipment and supplies

Compressed Air
Air under pressure greater than that of the atmosphere. Compressed air provides power for some tools. It is used in coal mining tools to reduce the danger of an explosion caused by a spark from an electric tool. See Air Compressor.

In 1700, French physicist Denis Papin first compressed air, using power from a water wheel, and transmitted the compressed air through tubes. Credit for the first practical application of compressed air is usually given to British inventor George Law, who in 1865 devised the rock drill, in which an air-driven piston operated a hammer tool.

Compressed air motors are widely used in tools in which occasional large forces are required, such as jackhammers; in hand-held tools where an electric motor would be too large, such as wrenches used to tighten lug nuts on automobile wheels; and in small high-speed rotary systems when speeds of 10,000 to 30,000 rpm (revolutions per minute) are required. A stream of compressed air can also be used to carry other materials, such as paint, and spray them through a nozzle.

Graffito, artistic technique of producing a design by cutting into or through a surface layer of paint or plaster to reveal a contrasting undercoat. True graffito techniques are found primarily in ancient, medieval, and Renaissance art, but the term is usually extended to include any technique that involves scratching a design on stone or plaster with a sharp instrument. Graffiti are abundant in ancient Egyptian and Roman art and have been found in Pompeii and the Roman catacombs.