Classifying Fibers

Identifying fibers is an important and vital duty of any crime lab, a function that is very time sensitive as well. Scientists say that fibers can fall from and be completely disconnected from a suspect's clothing as early as four hours after a crime...meaning that anyone seeking to inspect them is always operating on a very short time window.

One of the first and vital parts of identifying fibers for the purpose of using them as evidence is classifying them. This is just the first step, identifying the material from which the fiber originates so that investigators can then search for matching fibers in an attempt to associate or disassociate a suspect from the crime.

There are three basic kinds of fibers, categories that an examiner will determine as a first step in using a fiber as evidence. These three categories are Natural Fibers, Manufactured Fibers and Synthetic Fibers each category possesses certain singular traits that set them apart from each of the others.

Natural Fibers
Natural Fibers originate from animals, plants and minerals. In essence if the item is taken and re-worked into a shape, even dyed, it is still considered a natural fiber as long as it originated from a distinct animal, plant or mineral. Natural fibers are quite common, most especially cotton which is the most commonly found natural fiber in clothing.

Manufactured Fibers
Manufactured Fibers originates when cotton or wood pulp is disintegrated for its cellulose. The cellulose is then regenerated and reassembled into various combinations that cumulatively create artificial and manufactured fibers. Rayon and acetate are both examples of manufactured fibers.

Synthetic Fibers
Synthetic fibers originate from chains of monomers, or rather, polymers. These polymers are woven together through thin spinners that convert them to threads and that are then hardened and woven into different cloths. Sample synthetic cloths are nylon and polyester.