Abstract: In accordance with an illustrative embodiment of the present invention, a high capacity machine for washing industrial mats or rugs and the like comprises a generally rectangular tank divided by internal partitions into two wash sections and two rinse sections. An endless belt conveyor system attached to the top of the tank serves to move the mats over the tank sections with the nap of the mats facing down. Transverse header pipes in the tank sections are provided with rows of nozzles that form high velocity sprays of liquid which impinge against the nap to effect the scrubbing and rinsing action. The nozzles are directed at angles of 35.degree. forward and rearward with respect to the plane of the mat, with the nozzles which provide the detergent sprays having orifices that form flat or knife-like sprays to effect a deep cleaning of the nap, while the nozzles which provide the rinse sprays have orifices that effect diverging sprays to flush the detergent and particulate matter out of the nap.