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SCREEN Ink
Think before you ink
Some things in life are constant, including, it seems, the presence of ink.
Despite its ubiquity, however, ink technology is constantly changing resulting in
more choice for the print professional By Peter Kiddell
T
wo major changes have influenced ink solvent based, they consist of an ink base and the curing ink film does not drop below five
development in recent times: the a catalyst. The two are mixed together at a degrees Centigrade as this can stop the curing
abolition of heavy metal pigments such specific ratio and drying is a combination of chemical reaction, which cannot be restarted.
as lead, cadmium and chromium and the need solvent evaporation and the polymerisation Once fully cured a drop in temperature will not
to diminish solvent use. Both changes have between the base and the catalyst. Left to dry be damaging.
been driven by the imperative to reduce Health at room temperatures, they can take several Alongside these systems are baking inks,
and Safety and Environmental hazards. days to cure. Heat reduces the time and oxidation drying, sublimation, textile inks,
These and other factors, such as a change in improves the product resistance. adhesives and specialist mediums adapted for
pigment source, mean that formulations can The cured ink film boasts a high chemical printing.
change over the years. One thing is certain: ink resistance to solvents, acids and alkalis and The main determining factor for choosing
makers take their responsibilities seriously and can withstand high temperatures. It is ink is the facilities available for drying and or
will do everything possible to provide particularly suited to metals, glass and curing. Assuming the correct means of
consistent formulations. The UK boasts a rich ceramics. drying/curing is at hand, the next question is
vein of specialist ink manufacturers, including A useful tip with two component ink whether the ink will stick to the desired
Small Products, Davison Chemographics and systems is to ensure that the temperature of substrate and whether the printed results will
Apollo Colours while the multi-national players
such as Sun Chemicals and Fujifilm Sericol still
sit astride the screen printing market.
Screen printing is an ink friendly process and
there are a selection of ink chemistries
available so most people use one or two
different types of ink without really knowing
what is available.
Choose wisely
The greatest division is between radiation
cured and solvent based inks. Ultra violet
curing is the most common kind, with
microwave and electron beam curing in
specialist applications. UV cure inks are fast
drying and because of the lack of solvents will
stay open in the screen mesh for some time.
They will only dry when exposed to high
intensity ultra violet light.
Of the other ink types, water based ink and
reactive curing two part inks are the most likely
to be used. Reactive curing are generally the
most resistant ink systems available. Often Basic constituents of UV curing ink
10 SCREEN PROCESS AND DIGITAL IMAGING l January 2010 Visit us at www.spdi-online.com
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