The plate consists of precision grooves which are inked with a hand-drawn scraper. In this way the ink film is laid down and cleaned up quickly. The thickness of the ink film is controlled at known levels and variables of roller distribution are eliminated. The Wedge Printing Plate can be designed to produce either variable or uniform film thickness. The variable models produce a continuous range of film thickness in a single impression. Whereas the uniform film thickness plate is used when testing for a large print area, a multi-path uniform model allows several different levels of uniform film thickness to be proofed simultaneously. Strict attention to printing speed and/or pressure is essential only when press testing for mottle, printing smoothness or pick resistance. Although proof press testing with the Wedge Plate is restricted to solids, its ease and speed of operation make it a valuable routine control tool.

It should be noted that the NPIRI-A is the same in range and calibration as the Number G-1 NPIRI Production Grindometer and can also be used to check grind and dipersions.