An Examination of the Digital Fibrograph Length Uniformity Index1

Abstract

The Digital Fibrograph length uniformity index is usually misinterpreted. The theoretical maximum for this index is 51.28. The theoretical maximum index requires that: 1) all cotton (Gossypium sp.) fibers within the beard being scanned by the Fibrograph have the same length, 2) that the fibers are randomly caught and held, and 3) that the optical scan of the beard begin at the point of holding. The latter condition does not exist, because the scan of the beard begins at 3.81 mm from the point of holding. The result is that maximum possible uniformity index is increased to 56.0 for 40 mm and to 60.7 for 20 mm fibers. Direct comparisons of the uniformity index are valid only in a narrow range of fiber lengths.