|
Polylith
is the printer friendly synthetic paper that prints
bright, rich, vibrant graphics easily on lithography,
flexo, letterpress, and screen presses. The following
printing tips and techniques briefly summarize
our experience and recommendations. If additional
technical support is needed, please contact us.
Offset
& Letter Press
Standard paper inks can be applied in most cases;
however, it is recommended that a test be carried
out prior to printing. Sharp prints with excellent
reproduction of line and tone detail can be readily
obtained using a screen size of up to 175 mesh.
When satisfactory standard paper ink is not available,
the use of special inks is recommended.
High
solids inks are a good choice, and complete drying
is recommended prior to additional processing
to avoid ink distortion and offsetting. The leading
ink manufacturers have been consulted and inks
are available for lithographic, flexographic,
letterpress, and screen-printing. The following
information on printing, finishing and handling
Polylith synthetic papers is provided to ensure
the optimum results.
Ink
Selection
For regular jobs, many standard paper inks are
satisfactory, provided the ink-water balance is
reasonably well controlled. When close register
multi-color work is involved, the use of standard
paper inks with their high solvent content may
result in unacceptable print distortion, especially
on the lighter weights.
In these cases, it is recommended that high solids
special inks be used which have a very low mineral
oil content, and are allowed to dry entirely by
oxidation.
| Feeding
|
| 1.
|
The
most suitable printing speed is 8,000 - 10,000
sheets. |
| 2.
|
Before
feeding, it will be best if you can fan the
sheets or blow air to separate the sheets.
|
| 3.
|
If
the humidity is low, it is easy to generate
static. When feeding Polylith maintain the
relative humidity above 50%, and use anti-static
equipment to control static. The location
of static ionization units will have an effect
on their functioning. The use of static eliminating
tinsel on the delivery section can also help
reduce static build-up. |
Plates
Metal plates and pre-sensitized plates are preferable,
although paper/melinex plates may be used. Care
should be taken when using paper/melinex plates,
as some fount additives may retard or inhibit
drying. Experience has shown that plates with
a surface grain (anodized) will enable the printer
to obtain better control of dampening than plates
with a grained surface.
Fountain Solution & Dampening
Control of dampening is the most important factor
affecting the litho print quality. Use a 11% -
15% alcohol fountain system, or you can add other
alcohol substitute additives to the fountain system,
which will improve print quality. It is recommended
that the PH value of the fountain solution be
maintained between 5.5- 6.0. Temperature should
be maintained between 48�F - 59�F (9�C - 15�C).
Because Polylith is not absorbent as paper, the
amount of water on the plate should be reduced
10 -20%, or it will be slow to dissipate and will
retard ink drying.
Anti
Set-off Spray
It is recommended that a fine spray powder be
used with a particle size of 400 mesh, instead
of the regular 300 mesh and non-varnishing, starch-based
type. Please be advised that varnishing grades
or soluble powders are not recommended, because
these types can't provide adequate protection
against set-off.
Stacking
It is recommended that the height of synthetic
paper piled on the paper receiver shelf should
not exceed 7-8 inches. A desirable height is about
6 - 7 inches. Paper stack height is generally
about 9 inches. Leave the printed stack undisturbed
until dry.
Drying
Allow at least 3 - 5 hours drying time before
further printing to avoid ink offsetting. Also
allow at least 12 hours for complete drying before
cutting, coating and processing. UV drying methods
with the appropriate UV inks, as well as electron
beam and infrared drying methods can reduce drying
time. During drying, the temperature should not
exceed 150�F to maintain dimensional stability.
Print Pressure - Can be reduced 5-10% as compared
to paper.
Screen
Printing
Oxidizing inks that dry by evaporation are recommended.
Inks drying by oxidation should be put on racks.
If ovens are used for drying, temperatures should
not exceed 160�F, and be constant. Always use
the finest screen and thinnest ink film for the
best results.
Flexographic
Printing
Polylith can be readily printed by flexography.
Both solvent based and water based inks are suitable
and available from most ink suppliers.
Gravure
Printing
Polylith synthetic papers can be printed on sheet
or roll fed gravure presses, approved inks are
available from most ink suppliers
|
