Determining Correct Exposure of Lithographic Printing Plates.

An objective and quantitative laboratory method has been developed to determine correct lithographic plate exposure defined as accurate halftone reproduction. The method is based on comparing actual reflection densities of halftones to those predicted by an equation relating dot area to density. The method has been computerized but is readily adaptable to a desk calculator. Applications to DuPont/Lydel photopolymer lithographic printing plates are described.