Some Experimental Techniques for Studying the Fluffing of Printing Papers.

The terminology in the literature is confused, and little or no experimental work has been reported. This paper defines fluffing and gives a detailed account of four experimental techniques that have been developed to study the problem. For investigations in printing works a microscopic analysis of the deposit on the offset blanket, preferably in situ, together with an analysis of the paper in use, has proved most valuable. It has been shown that some types of fibre leave the sheet preferentially, and that trouble is caused by the unprinted side of boards and one-side coated paper. A rapid technique for determining the amount of loading in the two surfaces of paper has established a connection between the amount of loading in the side being printed and fluffing. The influence of printing machine variables on fluffing has been made possible by a method of measuring the quantity of fluff on the blanket in the presence of ink during controlled printing runs. Lastly, routine testing of small paper samples has become possible by the use of a fluff tester based on a new principle, i.e. the action of a dry offset blanket on the paper surface, under pressure.