SINGEING
Another important operation preliminary to
the scouring cotton piece goods, though not essential for all types of goods,
15 the removal of projecting fibers from the surface of the cloth by burning
known as ' singeing ' .with some fabrics it is sufficient to eliminate
dust by brushing and then shear or crop the loose ends of the yarn from the
surface ' but singeing is most effective and is almost essential for goods
intended for printing and for cloths which are valued for their smooth
appearance. Hence the various preparatory processes such as
( I ) Singeing ( for removal of projecting fibers’
)
( ii
) Desizing ( for removal of size )
( iii ) Boiling ( for removal of waxy
impurities ) and
( iv ) Bleaching ( for removal of natural coloring
matter ), may be considered in detail
SINGEING
Singeing is a process carried out for
removing ( by burning ) the loose hairy fibers’ projecting from the surface of
the cloth thus giving it a smooth appearance, Fabrics intended for printing
and other fabrics such as satin, sateen’s, poplin, handkerchiefs, etc . are
valued for their smooth appearance and therefore, require to be signed. Goods
which are to be mercerized are also singed in order to yield maximum luster in
the fabric. The need for singeing of fabric arises on account of the fact that
some of the fabrics which protrude from the surface of the yarn during spinning
and from the surface of the cloth during weaving give it a fuzzy appearance. The fabric to be singed should preferably be
dried before
singeing as wet cloth may get scorched during singeing. It should not contain acid-liberating substances like zinc chloride which may produce hydroelectric acid on heating and tender the fabric. Singeing should be carried out carefully without scorching or damaging the cloth. It is important to obtain faultless cloth after singeing. Three methods of singeing are commonly used depending on the type of singeing machine used these are
( 1 ) Plate singeing
( 2 ) Roller singeing and
( 3 ) Gas singeing Plate Singeing
In this method, one or two curved copper plates 2.5 to 5 cm thick are used. They
are set in the fire clay and heated by a furnace below to bright redness. The
cloth in open width is passed over and in contact with the red hot plate at a
speed of 150 to 225 meters per minute. The cloth is made to come in contact
with a constantly changing part of the plate by an automatic, device. The
projecting fibers’ are burnt when the cloth is passed over the plates. One or
both sides of the fabric can be singed during a single passage by properly
arranging the passage of the fabric. As there is direct contact between the
cloth and the hot metallic surface, a certain amount of luster is produced in the cloth due to friction.Plate Singeing
The heating of the plates has to be uniform otherwise singeing becomes uneven giving rise to stripes or bars which appear when the cloth is dyed later. It is difficult to maintain the plates at a uniform temperature which is a drawback of this method Another disadvantage is that when thousands of meters of cloth are run through the machine, minute grooves are produced on the surface of the metal which makes uniform contact with the hot surface difficult and thus gives uneven singeing. This defect is noticed after dyeing when the selvages are found to be dyed deeper than the body of the cloth. Further, as the surface of the cloth alone comes in contact. with the hot metallic plate, the fiber ends present in the interstices of warp and weft are, not singed since the intense heat does' not reach them.
After singeing, the cloth is quenched by
passing it through a mangle revolving in the water box to extinguish all
sparks.
