The grade mark of cotton is "grade+fiber length+micronaire value", for example, 328B means "third-class cotton with fiber length of 28mm(28-28.9) and micronaire value of B".
1. The smaller the number of cotton grades, the better the quality of cotton, similar to the saying that first-class products are second-class. Like the cotton we bought in the market to make quilts, they are all things that textile mills don't want, and they are generally below grade five cotton.
2. The fiber length is 28mm as the standard value, and the number 28 refers to cotton with an average fiber length of 28-28.9 mm ..
3. The micronaire value is an index to describe the fineness of cotton fiber, and the unit is "microgram/inch".
Therefore, there is little difference between the above 328B and 329B. The cotton fiber of 329B is slightly longer. Generally speaking, long-fiber cotton is slightly better, commonly known as "long-staple cotton".