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The aim of the study is to survey factors associated with the evaluation of paper coating heads in pilot-scale. Coating heads are often compared with regard to common paper technical properties like gloss and smoothness. It is questionable whether there are significant differences in pilot scale between coating heads as far as these properties are concerned. The coating trials showed that paper gloss and roughness can be controlled by the selection of a coating head but that there still are many detrimental factors affecting comparisons between coating heads. Thus, in pilot trials an effort should be made to make these factors as controllable as possible. In addition, it was shown that the choice of coating head has an effect on gloss variation. A short dwell coating head results in lower gloss variation than the other coating heads. The following parts of the study show that coating coverage makes a significant contribution to both gloss level and gloss variation. In consequence, it appears that the coating coverage difference between short dwell and longer dwell coating heads results in higher gloss level and gloss variability with the longer dwell time coating heads. It also turned out that it is difficult to characterize smoothness uniformity although optical surface profilometry gives valid information of the surface structure. This information seems to be even more valuable than the one concerning uniformity.
Experience the Power of Publications in the 2024 TAPPI Press Catalog
Sponsored by the Recovery Boiler Program R&D Subcommittee of the American Forest & Paper Association (AF&PA) and published by TAPPI Press.
The best-selling text to introduce the entire technology of pulp and paper manufacture.
A project of the Yankee Dryer Safety & Reliability Committee.
TAPPI Press offers some of the most in-depth resources and references for the forest products and related industries.
Available for Purchase – Conference Proceedings
TAPPI maintains a record of key conference papers, presentations, and other conference publications, available for purchase in a variety of formats.