ACRYLAC Special 835/05
Inking unit varnish.
Application
Applied from the inking unit of a sheet-fed offset press. Suitable for wet-on-wet and wet-on-dry
varnishing.
Special properties
Inking unit varnish with very good gloss development and good low-friction characteristics.
CAUTION
Surfaces coated with this varnish cannot be bonded with hot-melt adhesive. It is also not suitable for finishing
with hot-stampable film.
Specification
| |
570 835/05 |
Viscosity1 in s,
approx. |
25 |
Solids content,
approx. |
42% |
| pH |
7 |
| Specific gravity |
1.06 g/ml |
Heat-sealing resistance2
2 plies MS film
2 plies XS film
2 plies PP, PVC |
good
good
good |
| Rub resistance |
good |
| Application rate, wet3 |
2 – 4 g/m2 |
| Drying |
fast |
1. Viscosity as delivered, at 20 °C (DIN 53 211 draining time, 4 mm diameter nozzle)
2. 1 s, 150 °C (upper sealing jaw), 10 kPa (tested on Brugger’s heat-sealing unit,
material used for the test: coated cellulose card printed with magenta).
3. Depends on application method, card stock, and underprinting.
Cleaning
We recommend ACRYLAC Cleaner 10 T 0045
for cleaning rollers, rubber blankets, form cylinders, etc.
Special instructions
Maximum gloss will always be greater with wet-on-dry application than with wet-on-wet
varnishing.
• If moisture will be a factor, or if package contents may have detrimental effects on the pack-aging,
testing is strongly recommended. Double-sided varnishing (inline) entails a risk of
blocking in the pile. Mix thoroughly before using.
• Best drying results are achieved with the assistance of hot air and/or IR radiation.
Pile temperature should not exceed 30 °C.
• Adjust varnish delivery and cut out the backing so that no varnish can be transferred outside the
format. Otherwise varnish will be transferred from the varnish blanket or impression cylinder to the
blanket of the preceding inking unit. This will result in buildup and ink transfer difficulties.
• All inks used must be resistant to alcohol, nitro, and alkali (except Process Red).
• This varnish is not suitable for varnishing plastic films (polyethylene, etc.).
• Suitability for finishing with hot-sealing foil must be tested in practice. It depends on the
printing stock and the type of foil.
• Resistance to the heat of the various materials used for tools (e.g. metal) must be tested in
practice.
Processing instructions
Printers who are accustomed to working with oil-base printing varnishes must remember that
dispersion inking unit varnishes are very fast-drying products. When working with these
varnishes, the press must not be allowed to stand idle for more than a few minutes, since
otherwise the varnish will dry on the rollers and the rubber blanket. During startup and when
stopping for a few minutes, we recommend spraying Retarder 10 T 0422 sparingly onto the
inking rollers. For longer stoppages, the rollers, plate, and rubber blanket must be immediately
washed with water.
• Because of its low transfer rate, this varnish can be used
to only a limited extent – if at all – for spot varnishing. Areas at which no varnish will be picked
up during printing must be kept as free of varnish as possible, to prevent drying. A backing sheet,
approx. 0.5 cm smaller than the print format, can be placed under the blanket for this purpose.
It is also useful to cut the plate to size on the sides (be careful of burrs). Use of a relief plate
may be worth considering. Lateral distribution should be reduced.
• Before varnishing, the inking unit and ink duct must be very
thoroughly cleaned to remove ink residues. We recommend using Cleaner 10 T 0023.
• When pouring inking unit varnish into the ink duct, the
adjusting screws on the duct must be closed almost all the way. Sheet feeding and inking must already
be set up when the varnish is added. During setup, the adjusting screws must be wide open, since the press must run
at the highest possible varnish application rate to prevent drying. The varnish on the sheet
should feel not just tacky, but wet.
• If printing begins with too little varnish delivery, the first few
sheets will stick to the rubber blanket. If this happens, wash immediately with water.
Wait until the first few sheets are through before setting the adjusting screws for the correct
varnish delivery.
• There is no risk of the varnish drying in the ink duct.
• When working with inking unit varnish, wash only with water or with water to which
ACRYLAC Cleaner 10 T 0045 has been added. Cleaning agents used for oil-base inks are not suitable!
• Clean the inking unit very thoroughly when changing over from varnish to ink.
• After a press stoppage, the rubber blanket and plate should be washed and then sprayed with
• Retarder 10 T 0422 (spray bottle). Use the Retarder sparingly, since it slows down varnish
drying.
• Use starch powder for spray powdering.
• Sheets varnished with inking unit varnish cannot later be finished with UV varnish, since
complete curing of the UV varnish will be impaired by the high level of drying retarder in the
inking unit varnish.
