Runnability of the paper web during production and converting is a topic which has always concerned the pulp and paper industry. Good runnability at the lowest possible production cost is of primary importance to paper producers, converters and printers. This paper will review the literature on runnability and fracture of dry printing paper webs.
Several review articles have been written on this and related subjects. Niskanen  gave a thorough review of strength and fracture of paper. Niskanen reviewed the relationship between fibres, bonds and strength. He also discussed the relationship between web tension and fracture frequency before thoroughly describing the development of fracture mechanics methods. Kortshot  and Mäkelä  have also given excellent reviews of paper fracture and fracture mechanics. Roisum [4,5,6] has written reviews of the runnability of paper.
It is important to remember that many causes for paper web breaks are quite trivial. Paper rolls are damaged by transport and handling. Direct contact with water or condensation due to rapid temperature changes may give damage. Poor tape gluing may give web breaks during the flying splice. For many such problems the best procedure for improving runnability is to keep
the paper mill tidy, the floors clean and even. Further to follow and quality check the paper transport. Avoid gravel on the floor of transport containers, adjust the clamping pressure on the trucks used to handle paper rolls and so on. Yet even if the best precautions are taken, there will always be some damaged and weaker zones in the paper web. Thus, it is meaningful to use
fracture mechanics as a tool to investigate if such defects will develop to a web fracture at the web tension conditions used.
Much work on improving runnability of paper has been done based on the assumption that if the paper’s tensile strength, tear strength or fracture toughness is increased, then even the runnability will be improved. I will discuss this assumption and argue that the best way to improve runnability is to perform an engineering analysis of the converting or printing applica-
tion where the fractures occur. The important factors in such an analysis are web stress, defect size distribution and mechanical properties of the paper.