Yarn Evenness Testing | USTER Evenness Tester E valuation of Evenness of Yarn: This could be defined as the variation in a yarn’s weight or thickness per unit length. Evenness of yarn is measured by the following methods. Visual Examination: In this method, yarn evenness is checked by wrapping it onto a black board in uniformly spaced turns to reduce the effect of optical illusions caused by irregularity. These boards are then checked under proper lighting using a uniform and unidirectional light. Normally visual examination is done without any comparison with a standard, though comparison could also be made with the ASTM standard if it is available. Nowadays more uniformly spaced yarn boards are prepared with the help of motorized wrapping machines. By way of these wrapping reels the yarn moves gradually along the tapered black board as it is revolved. Tapered black boards are preferred for evaluating or determining periodic faults. If there are period...
