A suitable finishing for materials that do not fray is

If a material does not fray, it means that it does not unravel or develop loose threads along its cut edges. For such materials, a suitable finishing technique is needed to prevent the cut edges from becoming worn or damaged. One common finishing technique is called pinking. It involves cutting the edges of the material with pinking shears, which are scissors with serrated blades that create a zigzag pattern along the edge. This pattern helps to prevent fraying and adds a decorative touch to the finished product. Therefore, the correct answer is "pinking."