**2.1 Fineness**

The fineness is very important part of each fiber. The thickness of fiber can be known from its width, diameter, and sectional area. But there are very few fibers that have a completely round sectional area. So it is difficult to get the perfect answer. Therefore, there is a number that shows the ratio of weight against a fixed length or vice versa, the ratio of length against a fixed weight. For example, fineness is indicated by Denier, Tex, or yarn count. The excellence of fiber quality is evaluated from its fineness.
