The strength of a yarn and properties of fabrics made from it depend to a great extent on the amount of twist given to it. Thus accurate determination of amount of twist in any yarn is of prime importance in assessing its quality.
The amount of twist given to any yarn is usually determined by untwisting a known length of yarn and finding the number of rotations of one of its ends relative to the other needed to remove the twists completely. The equipment used for determination of twists of a yarn is known as Twist Tester.
The JUSTYwist Tester consists of a set of clamps, one of which is rotating and the other fixed. The rotating clamp is driven by hand through a hand wheel and gear arrangement. A five-digit re-settable revolution counter counts the number of rotations of the rotating clamp.