The machine most widely used for papermaking, named for its English inventors who introduced it in the mid-19th century. It provides a wide range of papers from heavy board to light tissue and is of impressive size and complexity. Its unique feature is the traveling mesh belt onto which the slurry of fiber and water is run from the headbox. The wire was formerly a screen made of specially annealed bronze and brass in 55–85 mesh size range. This has largely been replaced by single and multilayer woven polyester-forming fabrics, which are plastic screens woven with approximately 0.20 mm polyester monofilament. The plastic-forming fabric is longer lasting and more adaptable. The sheet is formed on this wire almost instantly, most of the water draining through the interstices of the wire. After leaving the wire, the sheet (called the web) passes through the press section of the machine where a number of rollers express enough of the remaining water to enable the sheet to hold together. It then moves into the multiroller drying section. The dried sheet (4–6% moisture content) is then fed to a high-speed calender for compaction and finishing. The entire process is continuous and rapid, the machine often operating for several days without shutdown.See Calender; Drying; Paper; Couch Roll; Dandy Roll; Supercalender.
