Wool finishing(4.5 hrs)

1 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

MILLINGMilling is an essential process for

woolen material.

Also known as felting and fulling.

This is used to alter the appearance, body, elasticity and the strength of the woolen fabric.

2 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

MILLINGDifferent types of wool vary in their

ability to felt and this depends on:(1) Length(2) Fineness(3) Scaliness(4) Waviness

3 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

MILLINGThe object of milling is to make the

fabric fuller and denser as a result of which the woven pattern becomes more or less obscure (unclear, indistinct, or blurred).Both dyed and undyed fabrics are

milled.The milled cloth is suitable for

producing a raised finish.4 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

MILLING Milling is classified into two types:(a) Acid milling(b) Alkaline milling (including soap milling) Both are carried out in stock or in rotary milling machine. The three essential requirements for felting to occur are:(1) Moisture(2) Heat(3) Pressure

5 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

ALKALINE MILLING This may be carried out with soap and soda

ash or with alkali alone.Alkali is used when milling in the grease. It is actually a form of soap milling, where

the soap is formed by interaction between the alkali and the grease, instead of applied as such.

6 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

ALKALINE MILLINGThe fabric is wetted with sodium

carbonate at a pH of 9 to 11 and temperature of 38C.Suitable for unscoured wool of low quality.Not suitable for fine fabrics.Both scouring and milling are carried out in

one operation. 30% cost saving compared to soap milling.

7 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

SOAP MILLING It is the method most widely used. The cost is higher than greasy or acid milling. Softer cloths are obtained with much less risk of

damage. There is minimum wear and tear on both fabric and

machines. Soap solution of 8 to 10% at 40C is used. After milling, the material is given a short and warm

wash to remove all traces of soap.

8 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

ACID MILLING It is very suitable for heavy fabrics such as

felts for printing and paper-makingmachines.Also employed for colored woven goods due

to less bleeding of color. Sulphuric acid is the best milling agent. 0.2 to 0.5% of sulphuric acid at a pH of 2 and

temperature of 45C is used.After milling the fabric should be washed

thoroughly.9 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

ACID MILLING This method is used to mill cross breed wool which is

difficult to mill with soap solution. It is suitable only for animal fibers since it destroys

the cellulosic fibers and produces unwanted harshness. Before milling, fabric should be thoroughly scoured

to remove any traces of soap, as the soap precipitates the acid.

10 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

PERMANENT SET One of the most remarkable properties of wool is its elasticity,

which increases with the moisture content. When wool is stretched in cold water it is highly elastic. The behavior of wool which has been stretched for a time in

hot water or steam is different.

11 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

PERMANENT SET It becomes set and does not recover in cold water, even

in the absence of tension. This behavior has been utilized in textile finishing processes

and often described as permanent set.

12 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

PERMANENT SET The chief processes for imparting permanent set to wool are:(1) Crabbing(2) Blowing or Decatising(3) Potting or Roll-boiling

13 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

CRABBING Carried out to bring dimensional stability. To eliminate the strains developed on the fiber during

spinning and weaving. To eliminate the distortions like crocking and uneven

shrinkage.

14 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

CRABBING The degree of stress relaxation during crabbing depends on:(a) Fiber quality(b) Yarn twist(c) Cloth construction(d) Subsequent dyeing and finishing operations.

15 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

CRABBING Crabbing consists of winding the fabric on a roller under

tension on to a beam through hot or boiling water, containing a wetting agent. Then the loaded beam is rotated in the hot or boiling

bath for about 10 minutes. The fabric is then wound on another beam and the

operation is repeated.

16 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

CRABBING By this method, the fabric is set and does not get distorted

during the subsequent processing. The effectiveness of crabbing depends on:(a) Tension(b) Duration of the treatment(c) Composition of the crabbing liquor(d) Temperature(e) pH of the crabbing liquor

17 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

CRABBING Higher tension leads to the production of a papery feel

in the fabric. Too low temperature leads to inadequate setting. The pH of the should be maintained at 7. crabbing liquor

18 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

CRABBING Poor setting may take place if the pH becomes acidic. In the composition of the crabbing liquor, no alkali

should be added. The addition of alkali will damage the fabric. Prolonged crabbing with alkaline solution discolor the

fabric and impart a poor handle.

19 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

CRABBING Care should be taken while winding, as bad winding leads

to listing (cause to lean to the side). Creases should not be allowed to form while winding,

as these creases too will get set during crabbing.

20 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

DECATISING/BLOWING This is mostly meant for woolen fabrics, but today all

suitings are decatised. The cloth is subjected to the action of steam, which is

forced through the fabric under pressure. As the steam is applied to the fabric while it is in a state of

strain, a permanent set is produced.

21 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

DECATISING/BLOWING The purpose of blowing is to set the woven structure in a

regular and permanent manner. The lustrous effect being secondary, results from the

improved regularity of the structure, together with the slight flattening. The fabric is wound on a perforated roller whose

perforations are covered with a cotton or canvas wrapper.

22 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

DECATISING/BLOWING The winding takes place under tension, which must not

be excessive or pressure marks will result. A wide wrapper is the applied and the ends are firmly

bound with cord. Steam is blown through the roll of fabric for 8 to 15

minutes.

23 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

DECATISING/BLOWING The wool becomes plastic, strains are relieved to give a

stable balanced product. This state is fixed by cooling, which is usually carried out

by blowing cool air through the fabric roll. It is essential that the cloth should be dried before

removal.

24 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

DECATISING/BLOWING It may be necessary to re-wind the fabric and blow again, so

that both the ends receive the same treatment. This second treatment is usually of shorter duration as

the fabric is already hot. Wool fiber contains small quantity of Thiol groups (-

SH).

25 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

DECATISING/BLOWING These groups are converted into Disulphide bond (-S-

S-) by the reaction of wool with a reducing agent or by the action of hot water, steam or alkalis. This interchange reaction and hydrogen bond

rearrangement are important in wool setting.

26 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

DECATISING/BLOWING The effectiveness of decatising depends on:(a) Type of fiber(b) Time of contact(c) Amount of steam(d) Tension(e) Type of finish desired

27 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

POTTING/BOILING Used to produce a soft handle and a smooth glossy surface. The goods are treated on a perforated iron roller, whose

perforations are covered with a cotton or canvas wrapper. Fabric is wound on to this roller at full width and without

any creases. A certain amount of tension must be applied during the

winding process.

28 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

POTTING/BOILING The roll of fabric is then covered with a wrapper of

cotton or canvas and both ends are securely tied with cords. The rolls are placed vertically in a cistern (tank) of water

which is gradually brought to 60C. It is maintained at the same temperature for at least 3 to 5

hours or possibly 2 to 3 days.

29 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

POTTING/BOILING The goods are lifted from the cistern when the boiling is

complete and allowed to drain and cool in an upright position. The cloth is unwound and the process is repeated with

the centre of the roll on the outer layers.

30 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

BEAMING

Regarded as a mild form of potting. Used to remove crimps or other marks which have arisen

during scouring, milling or dyeing. The goods are run through hot water and stretched in the

direction of weft by an expander roller, before running onto a wooden roller or beam.

31 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra

BEAMING The goods are allowed to cool over a period of 12 to 48

hours. With light-weight woolens, steaming treatment may

replace hot water.

32 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra