Scouring process
The scouring process is the process of removing natural materials such as oil, wax, fats,
gum, etc. as well as added impurities during the fabrication process to produce
hydrophilic and clean textile materials. It is a vital process of wet processing.
Objectives of Scouring
1. The main purpose of scouring is to remove impurities from textile materials.
2. To make the fabric highly hydrophilic.
3. To make the textile materials in a highly absorptive condition without undergoing chemical or physical damage significantly.
4. To produce clean material by adding alkali.
5. To remove non-cellulosic substances in the case of cotton.
6. To make the textile material suitable for subsequent bleaching operations.
Scouring process of cotton fabric
The scouring process of cotton fabric is a chemical washing process carried out on
cotton fabric to remove natural wax and non-fibrous impurities from the fibers
and any added soiling or dirt. The scouring process of cotton fabric is
usually carried in iron vessels called kiers. The fabric is boiled in an
alkali, which makes soap with free fatty acids. A kier is normally attached, so
a solution of sodium hydroxide can be boiled under pressure by excluding oxygen
which reduces the cellulose of the fiber. If appropriate reagents are used,
scouring will also remove the shape from the fabric although desizing is often
considered a separate process before scouring and is known as fabric preparation.
Preparation and other finishing processes are mostly prerequisites. At this, stage even if very naturally white cotton fibers are yellow in color and
bleaching, the next process is necessary.
Scouring-bleaching recipe for cotton fabric:
Detergent:
1 g/L
NaOH:
3 g/L
H2O2:
6 g/L
Peroxide
stabilizer: 1 g/L
Sequestering
agent: 1g/L
Temperature:
80-100°C
Time:
1 Hour
Fabric
Weight: 80 Kg
M: L = 1:6
Scouring process of wool
When
we directly collect wool from a sheep is known as raw wool, greasy wool, or
wool in the grease. This wool contains a high level of valuable lanolin,
sheep's dead skin, and sweat residue, and generally also contains pesticides
and vegetable matter from the animal's environment. Before the wool can be used
for commercial purposes, it must be scoured. The scouring process of wool may
be as simple as a bath in warm water or as complicated as an industrial process
using detergent and alkali in specialized equipment. Potash is used in the
manufacture of soft soap for scouring locally produced white wool. In other
processes, vegetable matter is often removed by chemical carbonization. In less
processed wools, the vegetable matter may be removed by hand, and some of the
lanolin is left intact through the use of gentler detergents. Lanolin transferred
from wool is extensively used in cosmetic products such as hand creams.
Wool scouring recipe-
Detergent:
2 g/l
Soda
Ash or Alkali: 1 g/l
pH:
Around 10
Temperature:
55-60°C
Time:
30-45min
M: L-1:10
Scouring process of silk
The scouring process of silk is very important for getting flexible, lustrous, and smooth
silk. It is also called the degumming process of silk. Raw silk is white,
golden yellow, or yellow-green, whereas wild silk is light to deep brown. Raw
silk does not empower the luster and softness for which this fiber is known.
The gummy substance called sericin covers the fibrous material and fibroin
imparts a harsh handle and must be removed to bring out the flexible and lustrous
qualities. Sericin
and fibroin, the two components of raw silk, are both proteins, but the
different amino acids and accessibility are relatively different from theirs. The process for the removal of sericin
is known as degumming, boiling off, and, less commonly, scouring. Degumming also removes other substances like fats, oils, natural pigments, and
mineral components. The main degumming agent is soap. Boiling off or degumming
of silk is carried out just below a boil (90°C–95°C) in soap solution with or
without alkali according to the quality of the fiber.
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