Pressure Washing, hydrocleaning, or waterblasting, are terms which describe the use of water propelled at high speeds to clean surfaces and materials. By focusing and pressurizing the water stream, the force generated can remove films and materials such as paint from walls, metal, and highways, rubber from airfield runways, sealants and membranes from concrete and chewing gum from sidewalks.
A pressure washer or power washer is a high-pressure mechanical sprayer used to remove loose paint, mold, grime, dust, mud, and dirt from surfaces and objects such as buildings, vehicles and concrete surfaces. The volume of a pressure washer is expressed in gallons or litres per minute, often designed into the pump and not variable. The pressure, expressed in pounds per square inch, pascals, or bar (deprecated but in common usage), is designed into the pump but can be varied by adjusting the unloader valve. Machines that produce pressures from 750 to 30,000 psi (5 to 200 MPa) or more are available.