Abstract: Apparatus and a method are provided for working and finish-treating the surfaces of stones by jetting a flow consisting solely of water, at a pressure of 200 kg/cm.sup.2 or more, toward the stone surface which previously may have been cut by a gang saw or a circular saw cutting machine, bush hammered or dabbed finished, bush hammered and then dabbed finished, bush hammered and then flamed or directly flamed without being bush hammered so that the surface of the stones is roughed and crystal particles in the stones are exposed.

Abstract: A process is provided for separation of an asbestos-containing material from a surface to which the asbestos-containing material is adhered, while preventing floating of dust of the removed asbestos-containing material, the process requiring jetting of pressurized water from a plurality of nozzles to the surface at a pressure of at least 80 kg/cm.sup.2 so as to wet and remove the asbestos-containing material therefrom by the energy possessed by the pressurized water.

Abstract: A method for removing substances adhering to a surface such as a wall of buildings in which a nozzle head having a plurality of nozzles is rotated eccentrically and moved sidewardly when used. The diameter of each of the nozzles is selected so as to be within a range of 0.05 to 0.5 mm, the pressure to be supplied to the nozzles is 800 kg/cm.sup.2 or more, the total amount of water jetted from each of the nozzles is 12 l/min or less and the number of revolutions of the nozzle head is 800 to 4000 rpm.

Abstract: An ultra-high-pressure rotary water-jet gun capable of removing rust, scale, burrs, paint film and other unwanted deposits from the surface of metal, concrete and other materials. An air turbine serves to rotate an eccentric rotor within the gun housing. A high pressure water line passing through the rotor is connected to a nozzle head on which are mounted several nozzle tips. The nozzle head is rotated in a circular path by the eccentric rotor while directing the high pressure water jets against the work piece. A pneumatic circuit and a hydraulic circuit with certain controls are provided.