Home' FLEXO Magazine : August 2016 Contents roll. If it is on covers or storage shelves, it will increase the likelihood
of damage. Consider ergonomics to aid in a storage system’s ease of
use. Design an area that is easy to access and has sufficient room to
remove the rolls without them contacting or bumping into each other.
Shield your anilox rolls by covering them. Covers work great, but only
when they are actually covering the roll. Having them sit in a drawer
or on the floor will do you no good. The cleanliness of a roll cover is
also important, particularly with UV inks, where the ink can spread
when not cured.
WATER BASED INK CLEANING TIPS
One of the most common mistakes made when cleaning water based
ink is using just H2O. Operators may pull the anilox rolls and bring
them directly to the sink to be cleaned with only water.
Water based ink has a pH of approximately 8.5 -9 .5, depending on the
ink system. This pH level keeps the pigment particles suspended and
the ink functioning properly. Water has a pH of about 7 and when
used to clean up anilox rolls, it drops the pH of the ink it contacts.
This shocks the ink, throwing it out of balance and making it more
difficult to clean up. It can even lock the ink in the bottom of cells and
reduce the roll’s volume.
To aid in the cleaning up of water based ink, a cleaning solution with a
pH of two points higher than the ink is recommended. This pH level
helps to re solubilize the ink and makes clean up remarkably easier.
Please note: The maximum acceptable pH level of roll cleaners is 11.8
and exceeding that allows for potential damage to the anilox. Do not
fall into the misconception that if two points higher is good, then four
must be awesome. This is just not true; in fact, it is worse.
Another abused technique is the use of soak tanks. To increase pro-
ductivity during changeovers, the operators will pull the rolls out of
press and put them in a soak tank. The aniloxes sit in the tanks until
they are cleaned. The theory behind this is that by soaking the rolls, it
prevents the ink from drying. This is not a good practice and I do not
Why? The mystery solution in the tanks is usually just water and as
we discussed, this is not a good cleanup solution. If the pH of the
solution is high, it can damage the rolls, especially if they are soaking
for a while. This allows the cleaner to work its way through the ceram-
ic to the base metal of the roll. Many times, these soak tanks are used
for more than one ink chemistry and that only complicates the issue.
Different ink chemistries typically do not mix well and can cause
a cleaning nightmare by locking up the inks in the cells or creating
residues that are almost impossible to remove.
More often than not, these soak tanks are not cleaned on a regular ba-
sis. The solution on the inside looks like sewage with floating debris.
To make matters worse, the tanks are usually lined with dried ink.
Dried ink is extremely hard and if an anilox is rubbed against it, the
potential for a scratch is high. The use of soak tanks typically means
the gears and bearing of the rolls are being submerged in water or
cleaner. It is never a good idea to submerge gears and bearings—It will
only cause them to fail sooner.
UV BASED INK CLEANING TIPS
UV ink is cured, not dried. This curing process is started by exciting
the photoinitiators in the ink with intense UV lights at a specific
Some shops will pull their anilox rolls out of the press and let them sit
under shop lights. The lighting in your shop—whether it is fluo-
rescent or incandescent—contains stray UV energy to initiate the
crosslinking process of the photoinitiators. Granted, it is not as intense
as the bulbs used in press, but it will begin to cure the ink. The longer
you leave the rolls exposed to the light, the more the ink will cure.
The ink will not cure overnight, but over time you will see a reduction
in volume. Once the ink is cured in the cells, it becomes difficult to
remove it. I always recommend thoroughly cleaning the rolls if they
are not going to be used. At the very least, cover the rolls to prevent
the UV rays from reaching the ink.
When cleaning UV ink, it is also important to select a cleaner that is
formulated to break the ink down. I stay away from fast solvents for
cleaning, because they tend to cause more issues. Many UV cleaners
are a slow solvent, so they can get in and break down the ink. The
slow solvents do not evaporate quickly, so it is critical to rinse them
using an alcohol or a fast solvent.
“Do not fall into the misconception
that if two points higher is good,
then four must be awesome.
This is just not true; in fact, it is
“Granted, it is not as intense as the
bulbs used in press, but it will begin
to cure the ink. The longer you leave
the rolls exposed to the light, the
more the ink will cure.
94 FLEXO | AUGUST 2016
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