dyeing n printing presentation

1. Devanu Roy Choudhury (Roll No. 6)
Ishan Rastogi (Roll No. 7)
B.F.T. (V)

3.  Most common approach of printing
 Can be done on a white or coloured fabric
 If done on coloured fabric, it is known as
overprinting.
 The desired pattern is produced by imprinting dye on
the fabric in a paste form.
◦ To prepare the print paste, a thickening agent is added to a
limited amount of water and pigment is dissolved in it.
◦ gums or alginates derived from seaweed are used as
thickening because they are easier to wash out, do not
themselves absorb any colour and allow better penetration
of colour.
◦ Most pigment printing is done without thickeners as the
mixing up of resins, solvents and water itself produces
thickening.

4.  In this approach, the fabric is dyed in piece
and then it is printed with a chemical that
destroys the colour in the designed areas.
 Sometimes, the base colour is removed and
another colour is printed in its place.
 The printed fabric is steamed and then
thoroughly washed.
 This approach is on decline these days.

5.  A resist paste is imprinted on the fabric and
then it is dyed.
 The dye affects only those parts that are not
covered by the resist paste. After dyeing, the
resist paste is removed leaving a pattern on a
dark background.

6. There are various methods of printing in which
one of the three techniques - direct, discharge or
resist is used.

7.  The designs are carved on a wooden or metal
block and the size paste is applied to the
design on the face of the block.
 The block is pressed down firmly by hand on
the surface of the fabric.

8.  In this machine counterpart of block printing,
engraved copper cylinders or rollers are used
in place of hand carved blocks.
 With each revolution of the roller, a repeat of
the design is printed.
 The printed cloth is passed into a drying and
then a steam chamber where the moisture
and heat sets the pigment.

10.  Printing is done on both sides of the fabric
either through roller printing machine in two
operations or a duplex printing machine in a
single operation.

11.  It is done either with flat or cylindrical
screens made of silk threads, nylon,
polyester, vinyon or metal.
 The size paste is poured on the screen and
forced through its unblocked areas onto the
fabric.
 Based on the type of the screen used, it is
known as
◦ Flat Screen Printing
◦ Rotary Screen Printing

13.  The design is first cut in cardboard, wood or
metal. The stencils may have fine delicate
designs or large spaces through which colour
is applied on the fabric.
 Its use is limited due to high costs involved.

14.  In this form of printing micro-sized droplets
of pigments are placed onto the fabric
through an inkjet print head.
 The print system software interprets the data
supplied by a cademic_Textiledigital image
file.
 The digital image file has the data to control
the droplet output so that the image quality
and color control may be achieved.
 This is the latest development in textile
printing and is expanding very fast.

16.  Firm knots are tied in the cloth before it is
immersed in a dye bath.
 The outside of the immersed portion is dyed
but the inside is not penetrated.
 There are various forms of Tie dyeing like
◦ Ikat Dyeing - where bundles of warp and/ or weft
yarns are tie dyed prior to their weaving.
◦ Plangi Dyeing - the gathered, folded or rolled fabric
is usually held with stitching to form specific
patterns.

18.  It is a resist printing process.
 Designs are made with wax on a fabric which
is then immersed in a dye. The unwaxed
portion absorbs the colour.

19.  The design on a paper is transferred to a fabric by
vaporization. There are two main processes for this-
◦ Dry Heat Transfer Printing
In Conventional Heat Transfer Printing, an electrically
heated cylinder is used that presses a fabric against a printed
paper placed on a heat resistant blanket.
In Infrared Heat Vacuum Transfer Printing, the transfer
paper and fabric are passed between infrared heaters and a
perforated cylinder which are protected from excessive heat by
a shield.
◦ Wet Heat Transfer Printing
The Wet Heat Transfer Printing uses heat in a wet
atmosphere for vaporizing the print pattern from paper to
fabric.

20.  It is a direct printing technique where the
background colour and the design are both
printed onto a white fabric usually in a one
operation.
 Any of the methods like block, roller or
screen may be used.

21.  The fabric is coated with a chemical that is
sensitive to light and then any photograph
may be printed on it.

22.  Designs are imparted to fabrics by spraying
colours in a controlled manner through
nozzles.

23.  A pigment- resin mixture is spread on a
screen bearing the design and the fabric is
passed into an electrostatic field under the
screen.
 The pigment- resin mixture is pulled by the
electrostatic field through the pattern area
onto the fabric.

24.  It is roller printing applied to warp yarns
before they are woven into fabric.

26.  A misfit is a print defect caused by improper
alignment of the screens. Also known as “out
of registration,” misfits leave unprinted areas
in the design. For example, a green leaf may
overlap its black outline or print over another
color. Up to 10 % of printed goods designated
as first quality contain some level of misfit.

28.  A stick-in occurs when a small fiber or piece
of lint gets stuck in the screen opening. The
result is a small pen tip sized unprinted circle
in the design. A stick-in is very difficult to
see and often goes unnoticed during a long
run.

30.  A scrimp defect occurs when the fabric
creases underneath one of the screens during
the printing process. The pattern is then
printed on top of the crease, leaving a large
unprinted area when the fabric returns to its
relaxed state.

32.  Wicking, also known as flushing, occurs when
the printed area bleeds out into the unprinted
area. The result is a “haloing” or shadowing
effect around the outline of the pattern
design. Residual salts left in the fabric during
resin finishing and / or poor fabric
preparation often cause wicking.

34.  After printing some spots occur on printed fabric

35.  Can occur due to uneven roller or squeegee pressure while printing paste is
applied

36.  defect created by the print head’s movement
over the substrate.
 If the head is not properly aligned, or if the
substrate advances unevenly, the result is a slight
horizontal “band” or line of unprinted area.
 Banding can be reduced or prevented :-
◦ with nozzle redundancy and multiple passes by the
scanning print head.
◦ In addition, banding is naturally reduced by most fabric
substrates.

37.  occurs when the inkjet nozzle fails to send a
drop of ink onto the fabric. Similar to a stick-
in, the result is a small, unprinted area. In
addition to misfires, nozzle clogging also
plays a big role in digital defects.
 When an inkjet nozzle clogs, the pattern may
lose some or all of one colour. Fortunately,
the inkjet drop is tiny, and most misfires and
clogs are not seen if the printer has been
designed with nozzle redundancy.

38.  Fabric handling also plays a role in the creation
of defects with digital printing. Because most
digital printers use a scanning head to print
across the width of the fabric, the fabric must
remain perfectly still or the image can be
distorted.
 One of the biggest fabric handling related defects
occurs when the fabric buckles or gets wrinkled,
causing the scanning inkjet head to come in
contact with the fabric. The result is a nasty ink
smear and possibly a damaged print head.

40.  In woven fabrics, a horizontal band off-
shaded yarns extending from selvedge to
selvedge caused by differences in filling
yarn size or difference in tension of warp or
filing yarns

41.  colour in a dyed fabric which rubs off rather easily
onto other fabric surfaces. May be caused by
inadequate soaping at the completion of dyeing
cycle
 Most frequently occurring imperfections – result
from dyeing processes
 Due to faulty or improper dyeing procedures, OR
preparation of the fabric prior to dyeing, OR
imperfections in the fabric itself.

43.  loss of color from a dyed fabric when
immersed in a liquid. Liquid subsequently
becomes colored

44.  an expression referring to the fact the color
of the dyed fabric does not match the std.
color or referenced sample.

45.  shade change in fabric which appears as a
horizontal selvedge-to selvedge change.
Caused by a filling change (new filling
bobbin) or loom stop and subsequent start
up

47.  A discolored area on the cloth. Caused by
foreign matter such as dirt, grease, oil or
residues of sizing on the fabric being dyed.

49.  differences in the shade of a fabric from
edge to edge or one end of a fabric to the
other Called selvedge-to-selvedge (or
selvedge to center) shading or end-to-end
shading respectively.

50.  Places in the fabric which have been excessively
weakened, usually by exposure to processing
chemicals. When the entire fabric is weakened, it is
referred to as Tender goods. Also occurs in
printing and finishing procedures.