Preliminary development of a laboratory former for oriented sheets

The production of paper in the laboratory, where controlled forming conditi ons result in an anisotropic sheet of predictable properties that match tho se of papers made on commercial paper machines, is a long desired instrumen t for many researchers. A laboratory sheet former based on a novel interpre tation of the flow in the forming region is being developed to meet this ch allenge. The key sheet characteristics, for a given fibre stock, were ident ified to be formation and fibre orientation. The ability of this laboratory former to simulate commercial paper was assessed by a number of standard t ests. The sheets formed on the initial prototype (Mk I) confirmed that the conceptual design was worth pursuing, and that improvements to the control and operation were required. The design improvements made to the laboratory former resulted in a second device (Mk II), which produced oriented sheets in a repeatable manner with sheet characteristics comparable to commercial ly made paper. The practical difficulties encountered in the development of this device are discussed along with the solutions that were found.