The document describes the results of burn, solubility and microscopic tests conducted on various natural and synthetic fibers including cotton, linen, rayon, silk, wool, polyester, acetate and acrylic. Cotton burns quickly leaving a yellow afterglow and is soluble in sulfuric acid. Under a microscope, its longitudinal structure is ribbon-like and cross-sectional is kidney-like. Linen and rayon also burn and dissolve similarly to cotton but at different rates. Silk burns slowly and shrinks from flames, dissolving in acids and alkalis. Wool burns slowly with a smell of burning hair and dissolves in sodium hydroxide. Polyester and acetate burn slowly and are soluble in sodium hydroxide and sulfuric

1. Submitted To: Sir Imran Raza
Submitted By:Ammar Zafar Ansari
Discipline: AMM-1A

2.  By Burn Test:
 Ignites on contact with flames; burns quickly and leaves a
yellowish to orange afterglow when put out. Does not melt. It
has the odor of burning. paper, leaves, or wood. The residue is
a fine, feathery, gray ash.
 By Solubility Test:
 It is soluble in 75% of Sulphuric Acid
 Under Microscope:
 Under microscope it can be seen that the longitudinal structure
of cotton fiber is ribbon like, while cross-sectional is kidney
like.

3.  By Burn Test:
 Burn in the same way as cotton but less quickly as
compared to cotton
 By Solubility Test:
 At 20°C, 70% of Sulphuric acid dissolves linen.
 Under Microscope:
 Under a microscope, looks like having multiple
sided cylindrical filaments with fine pointed edges.
The filaments show nodes at intervals. It, in fact,
looks like a bamboo stick having joints that results
into a little unevenness.

4.  By Burn Test:
 Same as cotton, but burns slowly without flame with
slight melting;leaves soft black ash.
 By Solubility Test:
 At 20 °C, 60% sulfuric acid dissolves Rayon
 At 20 °C, concentrated (12 M) hydrochloric acid dissolves
Rayon; slowly
 Under Microscope:
 Rayon fiber has uniform diameter with glass like shine. If
delustered then rayon fiber shows marks similar to
pepper, when viewed cross sectionally. Viscose fiber of
rayon looks irregular when viewed cross sectionally.
 However they are controllable

5.  By Burn Test:
 Burns slowly, but does not melt. It shrinks from the flame. It has the odor
of charred meat (some say like burned hair). The residue is a black, hollow
irregular bead that can be easily to a gritty, grayish-black ash powder. It is
self-extinguishing, i.e., it burns itself out.
 By Solubility Test:
 At 20 °C, concentrated (12 M) hydrochloric acid dissolves Silk
 At 100 °C, a 5% solution of sodium hydroxide dissolves cultivated Silk
 At 20 °C, 60% sulfuric acid dissolves Silk
 At 45 °C, 75% zinc chloride solution dissolves Silk
 Under Microscope:
 Raw silk fiber, composed of two filaments, has elliptical shape under the
microscope. The two fine and lustrous filaments are shown clearly looking
like transparent rods with triangular shape. Wild silk or tussah fiber has
different appearance than the cultivated silk. It is flattened, coarse, thick
and broader fiber having fine, wavy lines all across its surface whereas
cultivated silk is narrower fiber with no marks on it.

6.  By Burn Test:
 Burns with an orange sputtery color, but does not melt. It
shrinks from the flame. It has a strong odor of burning hair or
feathers. The residue is a black, hollow irregular bead that can
be easily crushed into a gritty black powder. It is self-
extinguishing, i.e., it burns itself out.
 By Solubility Test:
 At 100 °C, a 5% solution of sodium hydroxide dissolves Wool
 Under Microscope:
 Wool fiber has irregular, roughly cylindrical, multi cellular
structure with tapered ends. Under a microscope, three basic
layers are shown- epidermis (outer layer), cortex (middle layer)
and medulla (inner layer). Medulla is seen only in coarse and
medium wool fibers and that too under a highly powerful
microscope.
 Under the microscope it looks like scaly corkscrews.

7.  By Burn Test:
 It will shrink from the flame and burn slowly giving off
black smoke. Has a somewhat sweet chemical odor. The
residue is initially a hard cream-colored bead that
becomes darker tan.
 By Solubility Test:
 At 100 °C, a 50% solution of sodium hydroxide dissolves
Polyester slowly (30 to 60 minutes).
 Under Microscope:
 Generally, polyester fiber is smooth, straight. It looks
round cross sectionally. However, with various finishing
processes, its appearance changes in context of texture
and luster.

8.  By Burn Test:
 Flames and burns quickly; has an odor similar to
burning paper and hot vinegar. Its residue is a hard,
dark, solid bead.
 By Solubility Test:
 100% soluble in acetone
 Soluble in 60-70% of Sulphuric Acid
 Under Microscope:
 Acetate fiber looks lesser irregular than viscose
rayon when viewed cross sectionally. It has
indentations that look like occasional marks when
viewed longitudinally.

9.  By Burn Test:
 Flames and burns rapidly with hot, sputtering flame
and a black smoke. Has an acrid, fishy odor. The
residue is a hard irregularly-shaped black bead.
 By Solubility Test:
 Dimethyl formamide dissolves acrylic.
 Under Microscope:
 Under the microscope the fiber is dog-bone shaped
with apparent cut ends while cross-sectional
structure is bean like.