Answer: Random variation means variation occurs in the textile material in indefinite order. Example: Neps caused by immature fibres and long thick places in the yarn. Periodic variation means variation occurs in the textile material in definite fashion. Example: Thick and thin place caused problematic roll and cots in the drafting zone.

Answer: Refer: Evenness ---> Effects of irregularity ----> Variance length curve

Answer: The yarn has to be wound on black boards with help of suitable mechanical device and compare with the standard yarn appearance board for Grade (ASTM standard Yarn Appearance board). Yarn Grade C = some larger neps and smaller neps, fuzziness, foreign maters more than B, more rough appearance than B.

Answer: Refer: Evenness ---> Method of measuring yarn evenness ---> 3. By Measuring Variation In Thickness Under Compression

Answer: The spectrogram is amplitude of periodic mass variation plotted against the wave length. With help of this diagram we can trace the likely cause of imperfections or faults in the yarn, i.e. to find out the faulty parts of the machine.

Answer: The optical method is measuring the diameter variation but the capacitance method measuring the mass variation per unit length. So measuring mass variation is best suitable method for measuring yarn Unevenness. Simply, optical method is claimed to be nearer to the human eye in the way that it sees faults, the capacitance methods it feels the faults. Refer: Evenness ---> Method of measuring yarn evenness ---> 6) Optical method (IR Method): Zweigle G580

Answer: As per the Uster Classimat II the following are the objectionable faults, Short Thick faults A4, B4, C3, C4, D3, D4 are objectionable faults. In stricter norms faults under A3, B3, C2, D2 are also considered as objectionable. Long thick Faults E & G are objectionable. Thin faults H2, I1 & I2 are more critical. Normally these faults will be cleared in winding process. If it is presents in the yarn, the warping and further performance will be poor, also it will lead bad fabric appearance.

Answer: Refer: Evenness ---> Method of measuring yarn evenness ---> 7. Yarn faults classification (Capacitance method)