and ultraviolet curing processes are
enjoying increasing popularity, with sales
increasing year by year. However. although the processes
are often thought of as interchangeable methods of drying
print, there is actually a world
in cost, complexity,applications and
the working practices required.
To fit an ultraviolet system
to atypical four-colour sheet-fed press would cost
000 and take from five to ten
days.To run the system,in terms of power
consumption. would cost about US$3.00 an hour
The process also requires alonger learning curve than for
infra-red. but for certain types of it offers advantages
of quality and speed which can easily outweigh the cost
and complexity of installation.
Fitting an infra-red system on the
same press would cost between US$10,000 and
US$25,000 and take about one day. with power consumption
costing from US$2.00
to US$2.50 per hour. However. probably
the most significant point about this process is that it does
not require any changes in working practices or press
Compared to a press which has no accelerated
facilities, an infra-red
system should reduce the time of print
three to four times, which is a particularly useful saving
when printing work-and-tum.
It also enhances gloss levels and can
reduce the spray powder by up to 70 per cent; rub
resistance isimproved by
some 10 per cent.
HOW IT WORKS
However. to achieve all this, you need to follow a
few basic rules; understanding the process will help you do
this. Infra-red driers work by heating the ink film through the
application of infra-red radiation. Heat is acatalyst to
any chemical reaction - in this
the oxidation/polymerisation of a
conventional offset paste ink and
infra-red light is a heat source.