wool finishes
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Wool finishing(4.5 hrs)
1 Ms.Chavi Goyal,DFT, Asst. Prof., NIFT, Kangra
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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