Identification of Cotton, Jute, Flax, Wool and Silk Fiber

Fiber identification:
Fiber identification is an important component to the textile industry, forensic science, fashion designers, and the automotive industry, among others. It may vary with industries and method. Now modern technology is used to identification of fiber. But sometimes, old method is the best from modern technology. Those who are related to textile industry, especially for textile engineers and fashion designers have to know about fiber identification. In this article I have briefly described about method of identification of natural fiber like as cotton, jute, flax, wool, silk fiber.
Fiber identification test
Fig: Fiber identification test
Identification of cotton fiber:
There are different tests which could be used for the identification of the cotton fiber. It is suggested to combine at least two or more different methods to reach an acceptable and reliable conclusion in practice.

Non technical testing does not require any special equipment or setting for identification of fiber such as:

Feeling test: Unresponsive, smooth and a soft hand to human skin, feels good against skin.

Burning test: The reaction of fibers to heat from an open flame is a useful guide in identification of fibers. Not melt, burn, smell like paper burning. The smell of cotton burning is like of paper burning because paper is also a cellulosic material.

Some technical tests are required for details identification of fiber:

  • Microscopic identification
  • Chemical test
  • Coloring with dyestuffs solution
  • Solubility test
Microscopic identification: Kidney shaped cross-section and natural convulation of longitudinal view easily identified cotton fiber.

Solubility: Cotton is easily dissolved by H2SO4.

Identification of jute fiber:
There are different tests which could be used for the identification of the jute fiber.

  • Feeling test: Stiff and a harsh hand to human skin, feels bad against skin.
  • Burning test: Not melt, burn easily, smell like paper burning, because paper is also a cellulosic material.
  • Microscopic identification: Polygonal shaped cross-section and many ultimate cell of longitudinal view identified jute fiber.
  • Solubility: Jute is dissolved by H2SO4.
  • Staining: To study the morphology of fiber surface.
Identification of flax fiber: 
Following tests are done for identifying flax fiber.
  • Burning test: Combustion quick, bright, with afterglow.
  • Smell: Like burnt paper.
  • Residue: Pale grey, powdery ash.
  • Microscopic view: Flax fiber can be identified by longitudinal and cross-sectional view of microscopic.
Identification of wool fiber:
Wool is a protein fiber which is identified with different test.

  • Physical test: The flame is steady but more difficult to keep burning. The smell of burning wool is like burning of hair.
  • Chemical test: Wool fiber dissolves in concentrated sodium hydro-oxide and sodium hypo-chloride and slowly dissolves in Nitric acid 70%.
Distinguishing wool from silk:
The use of concentrated cold hydrochloric acid and sodium hydro-oxide solution will dissolve the silk but the wool fiber swells.

You can also read: Difference between Wool and Silk Fiber 

Identification of silk fiber:
Identifying silk fiber by the following methods.

  • Burning test: The smell of burning silk is as like as horn or hair.
  • Combustion: Small flame, slowly self extinguishing.
  • Residue: Black, friable cinder, weighted silk leaves a crystalline ash. Where wool will have the smell of burning hair but the silk will have a much more disagreeable smell.
  • Sulphuric acid: Dissolves, destroyed.
  • Lithium hypochlorite: Dissolves.