How to identify the quality of polyester thread

Polyester Filament Yarn is widely used, whether it is in life or in industry. There are all kinds of polyester threads on the market. How can we identify its quality?
1. Look at the appearance. Carefully observe whether the tissue is a basic tissue or a changed tissue, whether the gap between the coils is loose or tight, and whether the hand feels soft or rough. You can also use both hands to pull the thread to see how elastic and extensible it is.
2. Look at the grade. Polyester threads can be divided into first-class, second-class, and third-class grades according to their quality. The quality of first-class polyester is naturally better than other grades of polyester.
3. Look at faults. If there are many defects in the appearance of the polyester thread, the quality will not be very good, and the defects will also affect our use.