Scouring in textiles is a process that involves washing and cleaning raw fibers or fabrics to remove impurities, such as oils, waxes, and natural substances. This preparation step is crucial before further treatments like dyeing or finishing can occur. Scouring improves the fabric's absorbency and ensures better adherence of dyes and finishes. It typically involves the use of alkaline agents and surfactants to break down and remove unwanted substances.

1. PREPARATORY
PROCESS
SCOURING
By Mrs J.Athirstam

2. SCOURING
After desizing the cloth contains oils, fats, wax and colouring
matters. These components affects the absorbency of the
cloth. “Scouring” is the textile term for cleaning fibers
prior to mordanting and dyeing, and does not refer to
washing fabrics in a washing machine. If the fiber is not
clean, the mordant and dyes will not adhere well to the fiber.
Fabrics sold as gray goods or “greige” require a thorough
scour. It is also called as kiering. Boiling out is carried out in
a boiler in which yarn or cloth is boiled with alkaline liquors.
The scouring process consists in circulating hot alkaline
liquor (NAOH) usually under pressure (10-30 PSI or 1.5-2
kg per sq.m) through a regularly packed desized fabric for
upto 12 hours with temperature of 100-130 C).

3. Scouring objectives
⮚ In order to make the material extremely hydrophilic.
⮚ To considerably absorb textile products without suffering
chemical or physical harm.
⮚ A neat material is generated by adding alkaline.
⮚ For cotton removal of non-cellulosic material.
⮚ In order to make the textile material prepared for
subsequent bleaching.

4. The following main process of
scouring
1. Saponifible oils are converted into soaps.
2. Unsaponifiable oils and waxes are emulsified.
3. Proteins are hydrolyzed into soluble products.
4. Pectose and pectin are changed into soluble salts are pactic
or metapactic acid.
5. Simpler amino components are dissolved or hydrolyzed to
ammonia.
6. Mineral matter is dissolved.
7. Direct particles are removed and help in a stable form in the
kier liquor.

5. i) Saponification : It is the process in which fats are
treated with caustic which leads to the formation of
hydrophilic soaps.
ii) Emulsification : Waxes present in the fabric
cannot be removed in saponification. These are
esters of higher fatty alcohol and fatty acids.
Similarly mineral oils, lubricants cannot be
converted to water soluble product by boiling with
caustic. Thus the scouring solution must also
contain an emulsifying agent.

6. Types of Kiers
1. Open Kier
2. Closed kier
Some of them are vertical and others are horizontal.
Kiers are divided into three types
i) those heated by direct steam within the kier.
ii) those heated by indirect steam (closed coil)
within the kier.
iii) those heated by indirect steam outside the kier.

7. OPEN KIER
Grey yarn is also boiled in open kier under
atmospheric pressure using 2% caustic soda, 1%
soap and 1% sodium silicate (weight of the
material) using the ratio of 1:20 for 4-6 . Left
overnight in the liquor and washed thoroughly
with water.

8. Pressure kier: A kier is a cylindrical vessel (mostly
vertical) capable of holding 1 to 3 tonnes of cloth. A 2- tonne kier
having dimensions of 2.70 m in height and 1.95 m in diameter is
commonly used for alkali boiling. Either open kiers (working at
atmospheric pressure) or pressure kiers are used, depending upon
the material and process required. Coloured woven goods, for
example, are given an ‘open-boil’ and a milder alkali treatment.
When the lid of the kier is removed, it serves as an open kier
working at atmospheric pressure. Kiers are made of mild steel
plates 0.6 cm thick joined by welding or rivetting. They are
provided with a pressure gauge and a safety valve. High-pressure
kiers have manholes through which the cloth is introduced. As the
kier is made of iron, a ‘lime wash’ (with a mixture of lime, cement
and sodium silicate) is given to its interior to avoid the formation of
rust stains on the cloth when it comes in contact with the inner wall
of the kier.

10. Characteristics of kier boiler
Heating is done past times using high pressure level steam,
generated inwards an independent boiler instead of heating
past times straight boiler.
Iron in addition to steel accept the house of woods every bit
the stuff of structure of kier.
Improvement inwards the treatment of the goods past times
the usage of automatic pilling device.
Improvement of the circulation of kier liquor through the
stuff past times the usage of powerful pump.
Use of high pressure level kier shorten the duration of
boiling off in addition to thence saves the damage of the
steam, ability etc.

11. THANK YOU