56—Measurement of the Extent of Delustring of Filament Fabrics

A detailed study has been made of the reflection characteristics of fabrics woven from low-twist filament yarns. As a preliminary. pads of parallel yarn were investigated. It is shown that the main features of the reflection of light from fabrics can be explained in terms of the reflecting properties of the warp and weft considered separately as pads of yarn.The effect of delustring on the reflection characteristics of such pads and fabrics has been investigated; the results confirm the theory and establish the basis of the method for measuring the extent of delustre described and defined in an earlier paper of tWs series. In this method, the illuminated sample is rotated in its own plane and an orientation-intensity curve is obtained at a selected angle of collection. At this angle of collection, the unscattered reflection from the warp. The unscattered reflection from the weft and the scattered reflection can be separately identified on the curve. The ratios of unscattered light to scattered light are used as indices of delustre.