The identification of textile fibers is an important component to the textile industry, forensic science, fashion designers, and the automotive industry, and among others. However this process is quite common across different industries which is conducted very differently in each.
The American Association of Textile Chemists and Colorists (AATCC) lists microscopy as a way to identify fibers but it must be used with caution on manufactured fibers since they are created in a variety of modifications which alter their presence.
AATCC also lists ‘reaction to flame’ as a test method with the following categories for test reactions:
- Melts near flame
- Shrinks from flame
- Burns in flame.
ASTM International, in their volumes on textiles, lists infrared spectroscopy as the favored method for fiber identification and adds, ‘additional physical properties of the fibers such as density, melting point, regain, refractive indices, and birefringence that are useful for confirming the identification.
Identification of textile fibers are carried out in many ways. The most used ways are:
- Burning test
- Feeling test
- Microscopic identification
- Chemical test
To get the complete details for identification of fibers some other technical tests are also required:
- Microscopic identification
- Coloring with dyestuff solution
- Solubility test
Natural fibers like cotton, jute, flax etc are discussed below. Find it out!
Cotton Fiber Identification
Different tests can be carried out to test cotton fibers. For an acceptable and reliable result at least two or more different methods can be combined. Non-technical tests like feeling or burning tests don’t need any special equipment or setting.
Burning test: How a fiber reacts to the heat from an open flame is an important guide to the identification of fibers. It derives the results like not melt, burn, smell like paper burning etc.
Cotton fiber burns to produce smell like paper burning. Isn’t it interesting? Yes, paper is also produced from cellulose as like as cotton. 88-96% constituents of cotton is cellulose. It gives a rapid burning. There is no leftover ash from this test.
Feeling test: Cotton is smooth and soft hand to human skin that is unresponsive and feels good against skin.
Chemical or solubility test: Cotton is easily dissolved in 70% H2SO4 and cupramonium hydroxied.
Microscopic Identification: Cotton fiber is easily identified by its kidney shaped cross-section and natural convulation of longitudinal view.
Jute Fiber Identification
Feeling test: Jute fiber is stiff and harsh. The harsh hand feel of jute that feels bad against skin.
Burning test: It doesn’t melt. It burns easily that smell like paper burning. Jute has cellulose in its structure and paper is also cellulosic material.
Microscopic Identification: Jute fiber is identified by polygonal shaped cross-section and many ultimate cell of longitudinal view.
Solubility test: Jute is dissolved by 70% H2SO4 and gives a yellowish brown color.
Flax Fiber Identification
Burning test: Flax which is also a cellulosic fiber burns like paper. Quick and bright burning test with afterglow. Color of burning residue is pale grey. Powdery ash content is left.
Microscopic View: Microscopic longitudinal and cross-sectional view helps to identify the flax fiber.
Wool fiber Identification
Burning test: The flame is steady but more difficult to burn. The smell of wool burning is like burning of hair.
Chemical test: Concentrated sodium hydro-oxide and sodium hypo-chloride dissolves wool fiber. Wool also slowly dissolves in 70% Nitric acid.
Silk Fiber Identification
Burning test: The burning smell of silk is like horn or hair burning. The combustion is from small flame that is slowly self-extinguishing.
A crystalline ash is left by black, friable cinder or weighted silk. Wool burns like the smell of burning hair whereas silk burns with a more disagreeable smell.
Solubility test: Silk is dissolved by sulphuric acid and lithium hypochlorite.
Burning test: Polyester fiber melts on heating. It forms irregular beads and also gives a sweet aromatic scent.
Chemical test: Heated meta-crysol and heated ortho-phenol dissolves polyester.
Poly-amide fiber Identification
Burning test: These fibers are melted like glass. They also form beads. Again, their burning smells like amine.
Chemical test: Polyamide fibers are dissolved in cold meta-crysol, 60% sulphuric acid, 90% formic acid and hydrochloric acid.
Acrylic Fiber Identification
Burning test: On burning, this fiber forms small black beads.
Chemical test: acrylic is soluble in di-methyl formamide
Acetate Fiber Identification
Burning test: Acetate fibers melt on burning. This fiber gives vinegar or acetic acid like smell. Upon cooling, acetate fibers form small black beads.
Chemical test: Acetate fiber dissolves in acetone solution.