ORIENTATION OF FLOCS IN PAPER

By viewing a paper in transmitted light flocs of different shapes are visible as areas of higher basis weight They are mainly caused by phen omena in the headbox and sheet forming section. The orientation of flo cs can be measured by means of an image analyser and characterized by the two-dimensional Fourier transform. It can be shown that the coeffi cient of correlation between fibre orientation (Lippke-Tester) and flo c orientation amounts on average to 0.7 when profiles across the web a re compared. Flee orientation represents an individual property which corresponds in many cases to fibre orientation. Papers, particularly t hose which are made on hybrid formers, show a two-sidedness concerning flee and fibre orientation. The orientations have no significant effe ct on formation. Anisotropy or the extent of the non-randomness of ori entation is another important property besides the angle of the orient ation. Papers from gap formers have the highest anisotropy. Furthermor e, floc anisotropy leads to more significant variations than fibre ani sotropy.