WET-WEB PROPERTIES AND THEIR EFFECT ON PICKING AND MACHINE RUNNABILITY - PAPER MACHINES WITH OPEN DRAWS IN THE PRESS SECTION REQUIRE ADEQUATE WET-WEB STRENGTH

This report presents the main results from several of Paprican's proje cts concerned with the strength properties of never-dried wet webs and their influence on machine runnability and product properties. The re port shows that refining of chemical pulp greatly increases the streng th of webs made from pulp blends, and that the addition of unrefined k raft might not increase the strength of webs made from mechanical pulp s. The total draw of paper machine depends on the position of the firs t open draw. While most chemical additives including wet-strength agen ts, reduce the initial strength of never-dried wet webs, properly desi gned additives can increase the strength of wet webs made from chemica l and mechanical fibres.