Are there "forensic" tools that can typically be done at home to identify fiber content of yarn or fabric?

Question

An old question, Is there a way to determine the fiber content of a yarn if I've lost the label?, asked about identifying the fiber content of mystery yarn. The answer it received described a number of simple tests that identify broad categories of fibers.

For analyzing crime scene evidence, there are a number of forensic tools that can identify not only the exact type of fiber, but sometimes even the manufacturer. I imagine some of this work involves things like chemical tests that could not readily be done at home. However, much of it is as simple as looking at the fibers under a microscope and comparing that to pictures of different fibers. A microscope or strong magnifier is something many people have ready access to, or a camera or phone camera can often be used for this purpose.

Are there forensic tools, like simple microscopic examination, that can be done with basic equipment to which most people would have access, that would reliably and specifically identify the fiber content of mystery yarn or fabric?

For clarification, I'm generally aware of the nature of the forensic tests, but not the specific details. For example, I don't know whether a specialized microscope is needed for microscopic examination. I'm hoping readers very familiar with fiber identification or forensic methods can identify/describe techniques that would likely be accessible in a home setting to specifically identify fibers.

Answer 1

For most people at home a burn test is still the most viable option to identify unknown fabrics and yarns. With a little experience handling different types of fabric, it becomes easier to guess the fibers by look and feel than to employ forensic methods.

Forensic analyses use tools like microscopes with a much higher resolution than a phone camera can achieve (even with a gadget), polarized light, strong acids, infrared spectroscopy or gas chromatography. Also, from a forensic perspective the type of the fiber is often far less important than a comparison with a fiber from a different location that a suspect might have left there.

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There are 3 broad categories of fibers:

• Animal fibers (wool, silk, fur etc.) consist of proteins
  • Don't absorb water
  • Are covered in microscopic scales. Most fibers are 10 - 60 μm thick (1 micrometre = one millionth of a metre or 0.001 mm, or about 0.000039 inch), so you need a professional microscope to even see the scales.
• Plant fibers (cotton, linen, jute, hemp) consist of cellulose (a polymer made of glucose monomers) and include "regenerated fibers" (artificial fibers made from cellulose) like viscose and rayon
  • Absorb water
  • Can only be dissolved by a very strong acid (sulfuric acid)
  • The cellulose has a twist. Fibers of different plants can twist in different directions. Again, since fibers are microscopic, it's impossible for an amateur so see or test the twist of a single fiber.
• Inorganic fibers (acrylic, polyester, nylon etc) consist of inorganic chemicals (mostly carbohydrates)
  • Many can be easily dyed
  • Have very regular diameters under magnification.

Source material:

• Forensics Fiber Analysis
• Identification of Textile Fibers very interesting read with lists of characteristics of different fibers and microscopic images

I even found a Master’s thesis: Towards Recycling of Textile Fibers - Separation and Characterization of Textile Fibers and Blends by ANNA PETERSON. The chosen analytic methods are solid-state NMR [nuclear magnetic resonance] spectroscopy, IR [infra red] and Raman spectroscopy, none of which are doable by an amateur at home.