It is related to finishing process in textile.

2. CONTENTS
 Introduction Of Process Control
 Goals Of Process Control
 Objective Of Wool Fabric Treatment
 Scouring Of Wool
 Wool Bleaching
 Carbonizing Of Wool
 Milling (Or Fulling)
 Decatising Of Wool
 Crabbing Of Wool
 Process Control In Enzyme Finishing
 Bio Polishing
 Stone Washing
 Denim Washing
 References

3. INTRODUCTION
The concept of process control measures are becoming popular now days due to two main reasons:
 Growing competition and increasing cost of production.
 Textile industry now a day is facing a very stiff competition.
Under these circumstances, price and quality becomes important criteria, therefore, process control
becomes more essential foe achieving overall success.
Role of process control in wet processing is to achieve overall profit and higher efficiency. Certain tools
and standard process conditions are needed to control various phase of production.

4. GOALS OF PROCESS CONTROL
 Obtaining and maintaining optimum process condition.
 To minimize the wastage during process and form reproducible results.
 Establishing correct operating procedure.
 Setting up of testing sequence.
 Controlling production yield and waste.
 Carrying out adequate machinery maintenance.
 Accessing the department’s effectiveness.

5. OBJECTIVE OF WOOL FABRIC TREATMENT
The objective of wool fabric finishing is to develop the desired properties in wollen and worsted fabrics
that meet the specified end use requirements of consumers. Finishing is a sequence of dry and wet
processes that is carried out in a logical order. There are four main objectives to be achieved from the
finishing of wool fabrics.
 The removal, by scouring, of contaminants from the fabric. These contaminants may include
lubricants and antistatic agents employed in yarn and fabric production, warp sizes and lubricants,
machine oil stains, etc. In some cases the wool fabric may also contain vegetable matter (VM), in
which case the process known as carbonizing may be used to remove the VM.
 The development of the required handle, softness, fullness, drape, etc.
 The control of the dimensional stability of the fabric, e.g. relaxation shrinkage, felting shrinkage,
and hygral expansion.
 The application of functional finishes, e.g. antistatic agents, flame-retardants, waterproofing agents,
soil repellents, etc.

6. SCOURING OF WOOL
 The aim of scouring is to remove the contaminants from the wool fabric and to relax the fabric.
Depending upon the fabric type the spinning oil quantities present can vary from 1-2% (worsteds) to
10% (woollens).
 As a result of fibre migration during scouring, wool fibres migrate to the fabric surface, creating a softer
handle. Furthermore, consolidation of the fabric during scouring causes an increase in the cover of the
fabric.
 Wool fabrics may be scoured in either rope form or in open width form. The machines are designed to
provide the correct degree of mechanical action to aid the scouring action. Rope scouring machines
provide a better cleaning action but have the disadvantage that they can introduce permanent creases in
some fabrics.

7. ROPE SCOURING
The traditional rope scouring machine is known as the Dolly or Scouring Dolly.
 As can be seen in Figure the fabric rope circulates in a clockwise
direction, being lifted out of the scouring liquor, over the guide
roller, through the squeeze rollers, and then on back into the
scour liquor.
 The cycle then continues as the continuous rope is circulated at
speeds of up to 80-100 metres/minute.
 The liquor squeezed out of the fabric rope by the squeeze rollers
is collected in the trough underneath the squeeze rollers.
 During scouring, this liquor is returned to the bottom of the
machine. However, during rinsing, the squeezed out liquor is
directed to the drain.
RECIPE:
 Sodium carbonate: 3-5%
 Non ionic wetting agent: 0.5%
 Soap: 0.5%
 MLR: 1:20
 Temp: 35-40 degree celcious
 Time: 1h
 pH: <10

8. WOOL BLEACHING
The objective of bleaching is to destroy the natural cream and yellow pigments in wool using either oxidative or reductive
chemical processes to produce whiter wool. Bright white wool is required for certain market applications, e.g. baby’s
knitwear, and also for dyeing in pastel shades. Since wool itself can suffer damage by the action of oxidising and reducing
agents, great care must be taken in formulating the bleaching recipes.
 Hydrogen peroxide based bleaching recipes are commonly employed. Hydrogen peroxide is a very powerful oxidising
agent, with its oxidising power increasing with increasing pH.
 Wool is sensitive to damage at high pH, so the pH of the bleaching bath must be controlled to a maximum of about pH
8.0-8.5. A typical hydrogen peroxide bleaching recipe typically includes
Hydrogen peroxide (1-4 volume),
A wetting agent,
A pH buffering agent and
A stabiliser.
 The stabiliser is necessary because various heavy metal cations, e.g. copper, iron and manganese, can catalytically
decompose hydrogen peroxide.
 The wool fabric is normally entered into the cold bleaching bath, the temperature is then raised to 40-50oC, and held for
the required bleaching time (2-6 hours).
 Hydrogen peroxide bleaching may be carried out in rope form or open with form; and can even be combined with
scouring.

9. CARBONISING OF WOOL
Carbonising is the chemical process used to remove vegetable matter impurities from a wool fabric. The
vegetable matter may consist of burrs, seed and leaf matter from the shorn wool, and cellulosic fibres such as
cotton and jute fibres.
Wools with high vegetable matter content are usually carbonised immediately after raw wool scouring.
Checking concentration of sulphuric acid. Here titration method is preferred. Standard is 71-72% H2SO4. So
maintain proper concentration of sulphuric acid.
Dwell time for carbonization:
45 minutes. Ensure optimum dwell time.
Carbonizing efficiency:
Standard: It should be more than 99% actual standard is 99.7%.
Action: Change the acid, check the concentration.
Neutralization:
With the help of PH indicator. The fabric should be near neutral. Ensure complete neutralization of the fabric.
Generally sodium carbonate is used.
Local drying:
No local drying. To avoid the local drying increase the pickup of acid, and avoid undue exposure.

10. MILLING (OR FULLING)
 Milling is the finishing process that makes use of the natural propensity of wool fibres to migrate and
become entangled within the yarn and fabric structures. Milling, which is the controlled felting of
woven or knitted fabrics, is also known as fulling.
 The scale structure of the wool fibres, combined with their elastic properties in aqueous media, favours
preferential migration of the fibres towards their root ends. As a result, the fabric consolidates in both
the warp and weft directions and becomes thicker; leading to a higher mass per unit area.
 Milling also achieves reduced air permeability, increased strength and a hiding of the weave structure
(ie, high cover).
 Milling is achieved by intermittent mechanical action in the presence of a suitable aqueous liquor.
Milling can be carried out under mildly alkaline conditions or under strongly acid conditions, using a
suitable lubricant. Sodium soaps or synthetic detergents are used for alkaline milling whereas formic
acid is commonly used for acid milling.
 Milling machines include stocks, rotary milling machines and combined scour/milling machines.

11. ROTARY MILLING MACHINES

12. Alkaline Milling :
 This may be carried out with soap and soda ash or with alkali alone. For best results, the following
conditions may be used:
 Sodium Carbonate- 6-7%
 pH- 9 to 11
 Temperature- 38°C
 Time – 2.5 hours
 This is suitable for unscoured wool of low quality. It is not suitable for fine fabrics.
Process of alkali milling:
Scouring
Warm Water
Washing
Wetted with
Sodium
Carbonate
Solution
Transferring to
Milling machine
Final Scouring
Removal of alkali
and reducing
Temperature
Analyzing Result
Increasing
Temperature and
passing through
drafts

13. Acid Milling:
 Sulphuric acid is the best type of milling agent for this type of milling. For the process, the following
conditions may be used:
 Sulphuric acid- 0.2-0.5%
 pH- 2
 Temperature- 45°C
 Time – 2.5 hours
 But, the 0.2-0.5% Sulphuric acid is diluted with 2 pounds of dark oil, Vitriol for every 100 pounds of
cloth.
 After milling, the fabric should be washed thoroughly.
Process of Acid Milling:
Scouring Addition of acid
Transferring to
Milling
Machine
Pretreatment
with acid water
and
hydroextracting
Removal of
Alkali and
checking
neutrality
Increase of
Temperature
Checking the
result
Removal of
acid and
reducing
Temperature
Neutralizing
Final Wash

14. DECATISING OF WOOL
The aim of decatising (also known as blowing, open blowing or decating) is to stabilise the properties of a
wool fabric developed in finishing; including the lustre and handle achieved in pressing. It produces a
smooth, wrinkle-free finish and lofty handle in woollen and worsted fabrics and in wool blends with man-
made fibres. Heavier knits such as double jersey may be decatised.
Decatising can also be used to improve the crease-resistance of wool fabrics.
Pressure decatising is a setting process for wool and wool-mix fabrics that provides conditions for
achieving high levels of set. The principal objectives are:
 To stabilise lustre
 To set the fi nished aesthetics of the fabric.
 To stabilise dimensional stability

15. Decatising is usually the final finishing process, often carried out after steaming or some other shrinking
process, to ensure dimensional stability. Decatising should last through garment making, and beyond if done
under pressure. Most wool-rich woollen and worsted fabrics are decatised.
Figure shows a diagram of a traditional batch decatiser.
A traditional batch decatising or blowing machine

16. PROCES CONDITION OF DECATISING
 The process involves winding the fabric under controlled tension onto a perforated beam previously covered
with a wrapper) interleaved with a decatising wrapper.
 When the batch is complete, it is loaded into a steaming chamber, sealed and steamed under pressure.
 Typical conditions for wool fabrics are 0.8–1.0 bar pressure at a temperature of 120–125°C for two minutes,
followed by cooling to arrest the setting process.
 High levels of permanent set can be imparted, producing a ‘permanent’ finish. This is important for stability
of finish (to steaming during making up), for control of fabric dimensional properties, and for handle and
lustre.
 It is important that wool fabrics are at the correct pH and moisture content prior to all pressing and
decatising procedures, particularly pressure decatising.
 Fabric pH is ideally around pH 6 – stronger acidity reduces set, and stronger alkalinity may cause yellowing.
 Moisture content for all-wool fabrics is ideally 12–15%, since low moisture levels can result in low levels of
set.

17. CRABBING OF WOOL
Setting or crabbing is mainly applicable to worsted fabrics and is required to relax and set the strains
introduced into the yarns and fabric during spinning and weaving. If some weave structures are not set in this
way, they may be susceptible to the formation of distortions (e.g. ‘crows-footing’) during subsequent wet
finishing. The crabbing operation is carried out in the presence of heat and moisture, during which the
intermolecular bonds in the wool are broken and then reformed in a more relaxed configuration. Setting is
arrested by shock cooling.
The degree of stress relaxation during crabbing depends on:
 The fibre quality
 Yarn twist
 Cloth construction
 Subsequent dyeing and finishing operation.
Various methods and machines are used for crabbing. Crabbing fabric on traditional machinery is labour
intensive and slow, and care is needed to avoid problems in later piece dyeing. Modern machinery, such as
the Konticrab line for the continuous processing of piece goods, has largely overcome these problems.

18. KONTICRAB CONTINUOUS CRABBING MACHINE
 The open-width fabric is first treated with
hot water (80-100°C) or steam to relieve
tensions.
 Then the fabric is set at the correct
dimensions by passing it around the heated
drum whilst held by the endless rubber
blanket.
 As the fabric rotates, it is moistened,
heated, and pressed.
 Finally the fabric is cooled by the cold
water trough while stretched out, and
batched ready for the next process.

19. PROCESS CONDITION ON CRABBING MACHINE
In a traditional batch crabbing machine, the fabric is wound onto a cylinder (covered with a cotton wrapper)
which is rotated, whilst half immersed in hot or boiling water, for a predetermined time. To ensure even
treatment, the fabric is reversed and the treatment repeated. The fabric may then be steamed and finally
passed through a tank of cold water to arrest the setting process.
Two basic types of continuous crabbing machine are available.
 In cylinder types, the fabric is initially wetted through a trough of hot water and then passed around a
large, rotating, heated cylinder. The fabric is pressed at high pressure against the heated cylinder by a
specially engineered impermeable belt. Special seals resist escape of steam and entry of air at the
edges of the belt. Fabric operating temperatures as high as 135–140°C are claimed and superheated
steam is created in situ , setting the fabric. Setting is arrested by shock cooling.
 Superheated water machines differ in design from the cylinder types in having no pressure belt to
maintain fabric/cylinder contact and use superheated water to facilitate setting. A possible advantage
for fabric quality is that yarns are claimed to fully swell with minimal fabric compacting.
The fabric enters and exits through barometric columns. The temperature of water is around 110°C, although
a series of steam battery heaters situated around the main cylinder are claimed to elevate the fabric
temperature during its contact time with the cylinder, promoting fabric set.

20. PROCESS CONTROL IN ENZYME FINISHING
 Bio-polishing is a process to remove the protruding fibres of a fabric through the action of an enzyme. This
cellulase enzyme selectively acts on the protruding cellulose fibres and ceases to work after finishing the job by a
simple raise in temperature of the treatment bath.
 Cellulase are multi-component enzyme systems that are commonly produced by soil-dwelling fungi and bacteria.
The effects achieved by treating with these enzymes are pilling reduction, increase in softness and amelioration of
handle, surface structure, fabric appearance and dyeing yield..
 Acid cellulases exhibit the greatest activity generally in the pH range 4.5–5.5 at 45–55°C, whereas neutral
cellulases require a pH of 5.5–8.0 at 50–60°C.
 Generally a treatment of 45–120 min is appropriate, as prolonged treatment time may significantly increase the
fibre loss.
 Where acid cellulase predominates, required washing time is short (20–45 min), whereas for neutral cellulase a
longer wash time (45–120 min) is required.
 Excessive cellulose dosage and vigorous agitation may also increase weight loss.
BIO POLISHING

21. The bio-polishing process requires:
 Enzyme dosage: 1–5% on fabric weight (depending on the activity of the enzyme)
 Zywet NS: 0.2% (Non ionic surfactants)
 Liquor ratio: 5–15 L/kg of fabric.
 Time: 60–120 min (depending upon the amount of hydrolysis required).
 Temperature: 50–60°C.
 pH: 4.5–5.5 (For acid stable cellulase)
After treatment, the enzyme must be deactivated either by alkali treatment at pH 9–10 or by increasing
the temperature to 70–80°C and giving a treatment for ten minutes.

22. STONE WASHING
What is stone wash?
To achieve the desired stone washing effect for the garments, the stone should be of proper hardness, shape, and size. It
should be mentioned that, for heavyweight garments, large and hard stones are suitable. For lightweight garments, small
and soft stones are suitable. It is a popular garment washing.
The ratio of stone weight and garments weight is- [{(0.5 to 3)/1} kg]
during stone wash of any garments, the degree of color fading depends on some factors, such as- the garments to stone
ratio, washing time, stone size, and material to liquor ratio.
Stone washing times vary from 60-120min. Stones can be reused until they disintegrate completely.

23. PROCESS FLOWCHART OF STONE WASH
SL No. PROCESS PROCEDURE
01 Garments loading
with stone
It is the first process of stone washing; here the unwashed garments are loaded with the
required amount of stone.
02 De-size Garments are de-sized here by using a de-sizing chemical.
03 Rinse (Two times) After completing the de-sizing process, the garments should be rinsed at least two times
to remove the size material from the garments.
04 Stonewash Here, the garments should be washed until achieving the desired shade by using the
required chemical.
05 Rinse (Two times) After completing stone washing, the garments must be rinsed two times to remove
chemical and stone particles from the garments.
06 Softener Here softener is used for achieving a more soft effect on garments.
07 Unload the garments After completing all the above processes, the garments are unloaded here from the
machine.
08 Extracting Here the garments are extracted by using a hydro extractor machine.
09 Drying Finally, the clothing is sent to the drying section to dry all by using a gas dryer or steam
dryer.

24. DENIM WASHING
Denim finishing: In the traditional stonewashing process, the blue denim was faded by the abrasive action of
pumice stones on the garment surface. Nowadays, denim finishers are using a special cellulase. Cellulase
works by loosening the indigo dye on the denim in a process known as ‘Bio-Stonewashing’. A small dose of
enzyme can replace several kilograms of pumice stones. The use of less pumice stones results in less damage to
garment, machine and less pumice dust in the laundry environment; in addition, it’s possible to fade denim
without risk of damaging the garment.
 This process was conducted in liquor containing acetic acid (1g/l) at pH 5.5 and material to liquor ratio
of 1:30. The enzyme treatment was carried out at different concentrations of Genzyme SL (0.5 - 3.5%),
temperatures (40 - 70°C) and treatment time (20 - 60 min). After desired time the temperature was
raised to 90°C for 1 min to stop enzyme action.
 The denim garments were then washed with hot water then washed with cold water. Finally, garments
were softened with Textsoft softener (1 g/l) at 40°C for 10 min.

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