The effect of pulp pad dryness in determining brightness using non-standard fast drying methods

Abstract

In integrated pulp and paper mills a rapid pulp brightness determination method is needed at the pulp mill for quality and process control. In this study, the effect of dryness on the brightness reading of pulp pads has been studied. The results showed that in comparison with that from the TAPPI standard test procedure, the brightness was significantly lower when the pulp pad dryness was lower than 50%, implying that at pulp mills, the pulp pads should be dried quickly to a dryness of about 50% or higher in order to give rapid, yet reproducible brightness results. For this purpose, a forced hot air dryer was designed to dry the pulp pads to 50 to 60% dryness in about 15 minutes. The pulp pads which were dried with the forced hot air dryer had similar brightness readings to those prepared and dried by following the TAPPI standard method. Alternatively, a microwave oven can be used for the same purpose, and the pulp pads can be dried to about 50% dryness in 2.5 minutes.