In woven fabrics, curves and turns occur when the fabric is warped along its width. Weft threads are yarns extending across the width of the fabric. The warp threads extend through the fabric. If the fabric bends, the pattern in the middle of the fabric is slightly forward or backward. The curve is defined as the farthest distance measured between the dominant line and the straight line perpendicular to the edges.

There may be deterioration in the construction of the fabric, ie the yarn forming the fabric. If there is rotation in the fabric, the pattern on one side goes forward than the pattern on the opposite side. Rotation or skewness is defined as the distance measured between the other side of the dominant line and the point at which it meets.

The problem of rotation in the knit is a feature that must be checked before sewing the fabric. This problem leads to size multiplication. The spinning problem in the knit usually occurs after the fabric is washed or during the waiting period after cutting.

For the physical tests performed in the authorized laboratories, many standards published by domestic and foreign organizations are complied with. In this context, the standards used in the curve and rotation tests are as follows:

• BS 2819: 1968 Methods for measuring distortion in warped and warped fabrics
• ASTM D3882 Standard test method for curvature and rotation in woven and knitted fabrics

The required values ​​for wool knitted fabrics according to the standards are as follows:

• In woolen fabrics, 0,5 inch curvature and 1.0 inch rotational value should not be exceeded.
• In knitted fabrics, 0,75 inch curvature and 1.0 inch rotational value should not be exceeded.

The laboratories are required to carry out test and analysis studies based on their authorization from national or international accreditation bodies. Laboratories must be accredited in accordance with the standards of TS EN ISO / IEC 17025 General Requirements for the Competence of Testing and Calibration Laboratories.

At the same time, it is also important that they have state-of-the-art equipment and experienced and trained staff to ensure quality and reliable results.