sizing and de-sizing

1. SIZING
 Sizing is termed as “HEART OF WEAVING”.
 Sizing is the process of applying an adhesive coating on the
surface of the yarn.
 Technically it is the process of giving a process of giving a
protective coating on the warp yarn to minimize yarn
breakage during weaving.
 Sizing is mainly done on Woven fabrics, Denims garments
and Terry towels
 Sizing is applied into the yarn mainly to improve the weave
ability of warp yarn by making it more resistant to action of
weaving that are absorption, friction, tension and flexing.

2. ANATOMY OF SIZING MACHINE

3. Objectives of Sizing
To protect the yarn from abrasion
To improve the breaking strength of the yarn
To increase smoothness of yarn
To increase yarn elasticity
To decrease hairiness
To decrease the generation of static electricity


4. DISADVANTAGES OF SIZING
• The process is long and it takes time
• There is a risk of degradation of yarn
• The yarn diameter is increased
• Requires robust loom
• It increases yarn stiffness
• The fabric needs to be desized before use
• There is a risk of pollution
• Sizing changes the shade of coloured yarn
• 100% size material cannot be removed
• Size material presence leads to uneven dying

5. Types of Sizing
1. Pure sizing: when the size pick up % is about 3 –
10 % it is called pure sizing.
2. Light sizing: when the size pick up % is about 11 -
16% it is called light sizing.
3. Medium sizing: when the size pick up % is about
17 – 40 % it is called medium sizing.
4. Heavy sizing: when the size pick up % is above 40
% then it is called heavy sizing.

6. Desizing
o Desizing is the process of removing the size from
the warp yarns of the woven fabrics. Warp yarns
are coated with sizing agents prior to weaving in
order to reduce their frictional properties,
decrease yarn breakages on the loom and improve
weaving productivity by increasing weft insertion
speeds.
o The sizing material present on the warp yarns can
act as a resist towards dyes and chemicals in textile
wet processing. It must, therefore, be removed
before any subsequent wet processing of the
fabric.

7. TYPES OF DESIZING METHODS
DESIZING
METHODS
HYDROLYTIC
METHODS
OXIDATIVE
METHODS
NOVEL
METHODS

8. ANATOMY OF DESIZING MACHINE

9. OBJECTIVES OF DESIZING
 To remove the starch material from the fabric.
 To increase the absorbency power of the fabric.
 To increase the affinity of the fabric to the dry
chemicals.
 To make the fabric suitable for the next process.
 To increase the lustre of the fabric increase of dyeing
and printing.

10. PURPOSE OF DESIZING
Cotton is the most widely used natural cellulosic substrate.
Generally, the sizing agents are selected depending on the quality of yarn
and the fabric construction. The typical sizing agents used are natural starch
(maize, potato, wheat, tapioca, rice, arrowroot, sago) and modified starch
derivatives, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), etc.
However, during the subsequent process this applied size (surface coating
on yarn) has to be removed from woven fabric for further wet processing
comprising bleaching, dyeing, printing and finishing.
The purpose of desizing is to adequately remove enough of the size film to
allow further wet processing steps to occur at optimum efficiency. Thus,
desizing is considered to be a key parameter which determines performance
of further processing.

11.  Reduced absorbency
 Inadequate whiteness
 Paler dyeing
 Spotty dyeing
 Reserved marks in dyeing and printings
 Increased tendency to creasing due to hard handle
 Reduced tear strength
IMPROPER DESIZING LEADS TO:-

12. Thank you