Improving the wet web strength and runnability

This paper presents recent runnability research carried out in laboratory and pilot scale. Factors affecting adhesion, tensile strength, tension and residual tension after relaxation of wet web were studied. Adhesion of the web to surfaces was found to be - not only furnish specific - but also dependent on the temperature, dry solids content, chemical properties and contamination of the sur-face. Wet web strength has been shown to be a property even more sensitive to papermaking vari-ables than the dry strength. In addition to fibre and fines properties, also several chemical addi-tives have been found to improve the wet web strength. Also surfactant was found to have a con-siderable positive effect on wet web due to in-creased dry solids content after wet press. In-creased tension holding capability was found to require improved fibre network structure