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WHY IS ADHESIVE
COMING OFF ONTO THE GARMENTS ? |
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This is a common
problem that has most scratching their heads. Once the adhesive
is attached to the garment, the only way it can be removed is
by freezing the print and then cracking the adhesive off. Any
attempt to solvent wipe the adhesive off will result in solvent
stains.
Prevention is the cure, the following are possible
remedies:
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Water based adhesive applied to the pallets was not dry.
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Wet mist adhesive applied too liberally or thickly.
•
Incorrect adhesive used that is heat sensitive and transfers
under hot conditions only.
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WHY IS THE FABRIC
COLOUR BLEEDING & THE PRINTS DISCOLOURING ? |
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This phenomenon is due to residual or fugitive
dye that has been left in the fabric after the dyeing process.
This residual should be washed out of the fabric at the end
of the dyeing process, but often is not so as to save money
by cutting corners.
Possible methods to control bleeding:
•
Wash garments if problem too severe.
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Use low bleed inks systems or under-basing.
•
Print with catalysed water based inks that cure at
room temperature.
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HOW CAN I GO ABOUT
CHECKING EXPOSURE PARAMETERS ? |
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This is easily done
using a standard Exposure Calculator that can be obtained from
your photo-emulsion supplier. Special note must be made that
the exposure parameters for each mesh count and coating technique
will be unique and must be recorded as such. |
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WHAT CAUSES COLOUR
VARIATION FROM SAMPLE TO PRODUCTION ? |
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Most problems in batching up from sample to
production stage can be attributed to the touch colours contained
in the formulation. Careful note should be taken in the notes
contained elsewhere in this CD on “Colour Marching and
Recording”.
Possible problems could be:
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Dirty scale.
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Limitation of the sample scale — Tracking and
capacity.
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Mathematics — calculation problems.
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Poor mixing facilities.
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Poor recording of original recipes.
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HOW DO YOU CLEAN
UP PLASTISOL ? |
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The easiest solvent
to use is White Spirits or Mineral Turpentine. The PVC polymer
is insoluble in this solvent so the mixture does not become
a solution or adhesive! Furthermore, the White Spirits can be
recycled, as the PVC particles will settle out to form sediment
at the bottom, which can be collected after a time and gelled
before discarding. |
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HOW IS PLASTISOL
DISPOSED OF ? |
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As above, collect
any unusable plastisol and gel before discarding along with
other industrial waste. |
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HOW CAN I CHECK
IF THE PLASTISOL HAS CURED EFFECTIVELY ? |
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There are a number of
methods to check whether the plastisol has been gelled effectively.
The best method is obviously to perform a recognised Wash and
Rub Fastness test on the print. However, a quick scratching
of the surface of the print for "chalkiness" is an
early indication of under curing. Likewise, a quick solvent
wipe with a “spotting solvent” will indicate possible
curing problems. |
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WHAT CAN BE DONE
TO IMPROVE MATT DOWN ? |
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In order to improve matt down, you need to apply
ink with more “body” in order to hold down the fibres.
This can be done by:
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Printing through a lower mesh count.
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Printing through a screen with a higher tension.
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Use a softer durometer squeegee.
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Decrease the flood and squeegee angles.
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Slow down the print stroke speed.
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Use ink with higher filler content.
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Use ink with a lower gelling temperature.
•
Underbase the print.
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HELP, THE PRINT
IS CRACKING ! |
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This is either indicates
that the print is under cured or that the incorrect ink was
applied originally. If the print is under cured, pass the garment
through the curing process again to see if the integrity of
the print has improved. If the ink does not have the same stretch
value as the garment, more stretchable clear ink can be printed
over the entire print followed by the curing process again. |
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THE PRINT IS NOT
CURED - WHAT NOW ? |
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If the print is under
cured, pass the garment through the curing process again to
see if the integrity of the print has improved. If the integrity
has not improved, then a block print can be printed over the
entire surface and checked for fastness properties after curing. |
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