Part of a papermaking machine where a water suspension of paper pulp fibers is formed into a web of paper. The fiber solution flows from the headbox at the wet end of the machine, where the mixture is agitated to prevent premature fiber clotting, and delivered onto the continuous wire mesh belt of the forming section through the slice. Suction cup-shaped foils, rotating table rolls, or oscillation of the forming wire (called shake) drain water from the fibers. In a traditional fourdrinier machine, the forming section utilizes a single wire belt. The side of the paper that forms against the wire—called the wire side—has a different structure and texture than the top side of the paper—called the felt side. This two-sidedness of paper has deleterious consequences in many printing processes. Recent innovations such as twin-wire formers sandwich the fibrous solution between two wire belts, producing paper that has two virtually identical wire sides.
The forming section of the paper machine also contains a dandy roll, a wire-covered cylinder that may be used to stamp a watermark or the markings of laid finish paper in the forming paper web. The forming section ends with a couch roll, a perforated cylinder employing a vacuum to suck additional water from the paper web before it is sent to the press section of the papermaking machine. At the end of the forming section, the paper web is about 80:85% water.