A novel method to measure fiber kappa number

Uniform pulp helps bleaching efficiency and improves pulp strength. Few techniques are available to assess pulp uniformity. The authors present a novel method that correlates the intensity of stain induced fluorescence to the kappa number of single pulp fibers. Fibers of different kappa numbers can be differentiated using their fluorescence introduced by Acridine Orange staining. Acridine Orange stained fibers fluoresce a green color when they have a low kappa number. At higher kappa number. At higher kappa numbers, stained fibers emit fluorescence with a bathochromic (red) shift. To optimize the Acridine Orange staining procedure, the effects of stain solution concentration and pH, staining time, and fiber kappa number are quantitatively evaluated with a fluorescence microscope interface with an image analysis system. Application : a method to measure uniformity of a pulp down to the fiber level may be a tool to develop improved pulping technologies.