THE IDENTIFICATION OF PAPER CUTTING KNIVES AND PAPER CUTTERS.

This article focuses on the identification of paper cutting knives and paper cutters. Of the numerous problems confronting a large laboratory there will always be certain cases that are highlighted by their interesting background and importance. Paper is cut and trimmed commercially by large guillotine type machines, in which a manual or automatic clamp descends to compress the paper and hold it firm while a long hollow ground blade is brought down at great pressure through the stack of paper. The stroke of the knife has a sideway motion as it descends. Depending upon the type of shear stroke, single or double, the edge of the blade will be either parallel to the table top or higher on one end when it starts through a stack. A rocking motion close to the end of the stroke in a double shear action will bring the blade parallel to the table. This type of shear is more like a pair of scissors. A machine of this sort lends itself to the final process of printing where many duplicate copies of a single design are printed on a single sheet of paper, and many of these sheets piled together can be separated simultaneously. The manner of handling, storing, and mounting the knife may also be a factor in placing defects in the blade. Care must be taken to protect the edge at all times or the quality of the cutting will be lessened and the possibility of identification increased.