Abstract: Apparatus for spraying at least one finishing substance onto a material (such as leather) passing a plurality of spray booths having sprayer devices associated therewith. Various inputs relating to (a) sprayer device position, (b) the location and area of material on a moving conveyor carrying the material, (c) conveyor movement, and (d) other related inputs are directed to a single computer unit which communicates command signals which effect the closing of selected normally open valves corresponding to respective sprayer devices. The apparatus provides for limited overspray, accounts for delay following a computer command signal due to valve response time, and include various corrections related to embodiments having sprayer devices which move in nonrectilinear paths. A rotary transformer coupling for improving communication between the computer unit and the valves is provided in rotating sprayer arrangements which have a plurality of sprayer devices, each of which follows a circular path.