The definition and selection of your forming fabric ic design could mean the difference between success and failure in improving machine and fibre efficiency. By defining the too drainage surface characteristics of your current successful forming fabric, pu can evaluate the consequences of change. Using the PAPTAC G18 data sheet as a base, this paper will demonstrate the usefulness of an engineered approach in defining: Total top surface drainage area; Individual drainage hole (orifice) machine direction (MD) and cross-machine direction (CMD dimensions in I relation to fibre lengths; The importance of CMD yarn support to the fibre over machine direction thigh MD fibre orientation exiting the headbox); Beran Fibre Support Index.