By wrinkle-free is meant the ability of fabrics to return to their previous form when the pressure effect is removed after creasing under a certain pressure. The resistance of the fabrics, which are a textile product, to the wrinkles that occur during use and the ability to recover after this resistance is expressed by the crease-free angle.

Crinkle angle tests are carried out in order to determine the wrinkle ability of the fabrics which are wrinkle-free.

Cotton, linen and cellulose fabrics are very sensitive to wrinkling. Synthetic fabrics generally have better crease-free properties. Factors other than fiber type are effective in the creasing of fabrics. For example, if the fabric weaving density and twist is high, the tendency to wrinkle is lower. The harder the fiber, the more wrinkled the fabric and the harder it will recover. The more flexible the fiber, the faster the crease will disappear.

The elements that provide crease resistance are: fiber content, yarn structure, fabric texture and garment design. Therefore, wrinkle-free is a feature that is difficult to control.

The wrinkle-free angle is determined by measuring the unfolding of the fold, the fold recovery angle in the horizontally folded fabric.

For physical tests performed by accredited laboratories, many standards issued by local and foreign organizations are complied with. In this context, the standards which are taken as basis in wrinkle angle tests are as follows:

• TS 390 EN 22313 Textile fabrics - Determination of unfolding of a horizontally folded fabric by measuring the fold recovery angle
• AATCC 66 Wrinkle removal - Woven fabrics: Recovery angle

The laboratories that will perform the wrinkle angle tests must be accredited from national or international foreign organizations in accordance with the standards of TS EN ISO / IEC 17025 General Conditions for the Competence of Testing and Calibration Laboratories. It is also important that the laboratories have a technological infrastructure and an experienced and trained staff.