Apparatus for manufacturing spot test indicators

Claim 1

Apparatus for applying a predetermined pattern of an aqueous liquid containing a chemical indicator reagent to a flat, moving sheet having a hydrophobic surface, whereby a constant volume of the liquid is deposited on a constant area of the hydrophobic surface, which comprises; a fixed platen having a flat surface to support a sheet traveling thereover; means for feeding a flat sheet to the surface of said platen; means for drawing the sheet across the surface of said platen at an adjustable, fixed speed of from about 5 to about 20 feet per minute and within 1 percent of the set fixed speed; a header for mounting a plurality of liquid dispensing nozzles over the surface of said platen, said header being adjustable in a vertical plane and adapted to hold in a rigid position a plurality of said nozzles; a plurality of liquid dispensing nozzles mounted in said header; means for positioning the plurality of nozzles in the header a uniform distance above the surface of the platen and above the flat sheet drawn across the surface of the platen so that there is a gap between the moving sheet and the nozzles, said nozzles being set as close to the moving sheet as physically possible; and means for supplying to said nozzles an uninterrupted, pulse-free flow of the aqueous liquid reagent, at a constant volume rate of from about 2 to about 4 microliters per linear inch of the moving sheet.