1. Whether it is cationic modified polyester, or drawn yarn or low-stretch yarn, the flame color of polyester when burned is light red with aromatic odor.

2. Nylon, whether it is drawn yarn or low-stretch yarn, has an odor when burning. The flame color of white or light-colored nylon is light blue when burning, and the flame color of black or dark-colored nylon is light yellow when burning.

3. Acrylic fiber, whether it is drawn yarn or low-stretch yarn, has an odor when burning, and the flame color when burning is light red.

Using this point, we can identify these three kinds of fibers.