Fabrics shrink due to several reasons, including:

Natural fibers

Natural fibers, such as cotton and wool, are prone to shrinkage due to their structure. The fibers in natural fabrics are not uniform in length, width, and strength, which can cause the fabric to shrink when subjected to heat, moisture, or agitation.

Yarn twisting

Some fabrics are made from yarn that has been tightly twisted, which can cause the fabric to shrink when subjected to heat and moisture. This is because the fibers in the yarn are tightly packed together, which can cause the fabric to contract when exposed to heat and moisture.

Finishing treatments

Fabrics may also shrink as a result of finishing treatments, such as washing, drying, or pressing. These treatments can cause the fibers in the fabric to shrink, which can result in a reduction in size and shape.

Poor quality

Fabrics made from low-quality materials or using inferior production methods may be more prone to shrinkage due to the presence of weak or inconsistent fibers.

Improper storage

Fabrics can also shrink as a result of improper storage, such as being stored in a damp environment or being exposed to heat and light.

Overall, the shrinkage of fabrics can be attributed to a variety of factors, including the type of fibers used, the yarn twisting, finishing treatments, poor quality, and improper storage. Understanding the cause of shrinkage can help to prevent it and ensure that fabrics maintain their size and shape over time.