property>mass per unit length
What is Mass per Unit Length?
The mass per unit length is the linear density of a one-dimensional substance such as a wire or thread. Its practical application is in measuring the weight of threads and yarns in the textile industry.
Clearly if the SI unit were kg/m then most threads would have tiny values, so the SI unit is the more convenient Tex - the number of grams per 1000 metres. As might be expected in a specialized industry such as textiles, there are many industry-specific units of measurement in use. Some of these are defined reciprocally in terms of the length of thread needed for a given weight (see specific weight).
In addition to the Tex, a widely used unit is the denier, which is defined as the number of grams per 9,000 metres of thread. This unit is based on the definition of a single strand of silk thread which is one denier. Strictly this is the total denier, as opposed to the filament denier which refers to the linear density of the individual fibers making up the thread (also referred to as the DPF or denier per filament). The denier will also be familiar to those who purchase ladies stockings and tights, where it is used as a measurement of the thread weight and hence the opacity and fineness of the material.