Reference Book
3) Drop the form rollers to the on position.
4) With one hand holding each strip, pull towards you with a slow uniform
tension. There should be a slight even drag on both strips. If one strip
pulls easier than the other or if there is too much or too little drag on both,
adjust the roller on one end or both as a test procedure.
5) After pressure seems satisfactory, drop the form rollers to the plate and
lift it up again. You should see a faint damp line across the entire width of
the plate.
Waterless Presses:- A waterless press is an offset lithographic press system
that does not use a dampening system during the printing process. The surface
of a waterless plate is a layer of silicone rubber that repels ink and keeps the
non-image area separate from the image area. The image area is recessed. It
lies just below the plate surface and has an ink receptive photopolymer coating.
The silicone plate surface serve the same function as the fountain solution in a
dampening system. Waterless plates are designed from conventional
lithographic presses. Plate exposure is done using vacuum frame and light
sources and is developed with a water based solution
than with a solvent based solution which are more
safe to dispose.
Waterless plates require special inks which are
thicker than conventional lithographic inks. The
inking system used by waterless presses is
temperature controlled. As ink is applied to the plate,
the surface is designed to repel certain thickness of
ink. The system must regulate the temperature of
the ink to maintain correct thickness. Several rollers
in the system contain hollow tubes that are filled
with water to remove excess heat. Water circulate
through the rollers and cools the ink as it is
transferred to the plate.
Advantages of waterless presses
Waterless plates provide great image quality by producing a higher density of
ink when they are offset. The procedure involved in formulating dampening
solution and maintaining a dampening system are eliminated saving set up
time. Waterless printing changes the image transfer system from a chemical/
physical process to a mechanical process. Waterless printing system is more
eco-friendly compared to the conventional offset printing method.