Abstract
The measurement of paper uniformity is discussed with special reference to those methods providing information that may be used to investigate the sources of variation of structure and properties. The flocculation of fibres in the stock and the hydrodynamic properties of the head box are shown to be the major causes of heterogeneity.
Fibre flocculation is both a direct source of heterogeneity and a factor affecting the fluid mechanical properties of the stock. The flow properties of fibre suspensions are described on the basis of pipe flow studies and the significance of these studies to head box flow is discussed.
The head box is considered as a source of non-uniformity with some reference to the significance of secondary flows. Experimental methods are described that may be used to assess head box performance to investigate conditions that give rise to poor uniformity.
Areas in which further research is desirable are indicated.
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