Recognizing the ever-expanding variety (proliferation) of chemical
cleaners in the "Flexographic" industry, Harper Corporation has been diligent
in keeping abreast with what chemicals are utilized and the adverse effects of
improper application of these chemicals.
As an anilox manufacturer, Harper Corporation understands that the
use of chemical cleaners is a reality within the "Flexographic" printing
industry and plays a vital role in the production process. Based on Harper
Corporation experience with anilox rollers and chemical cleaners, it has been
observed that many of these cleaners are unnecessarily caustic to permit fast
and thorough cleaning. The corrosiveness does not make them a safe cleaner for
the anilox roll. We also have developed criteria below to address what can be
safe and what can be detrimental to the anilox. We advise our customers to
consult with us as well as the ink suppliers when using chemical cleaner(s) on
anilox rollers.
Several things should be taken into consideration when cleaning an
anilox roll. First and foremost, EPA and OSHA issues must be addressed.
Secondly, Material Safety and Data sheets (MSDS) should be reviewed. Third:
before using any chemical cleaner, you should consult with your anilox and ink
suppliers to determine if these chemicals can have a negative reaction with the
ceramic anilox roll or ink performance. Fourth: ceramics are porous and can
allow acidic or alkaline chemical migration through the ceramic to attack the
ceramic's bond between it and the metal base. Furthermore; if an end of a
roller and/or sleeve is chipped this is like an open wound accelerating the
corrosion process resulting in the ceramic blistering or delaminating. Fifth:
The majority of sleeves have "aluminum" cladding or other non-ferrous metals
and are a composite structure. Many lightweight narrow web rolls have aluminum
roller bodies. These materials by nature are more susceptible to damage from
acidic and alkaline cleaning chemicals than steel base. Many anilox chemicals
developed for use on a steel bases may not be suited for an anilox sleeve or
lightweight "aluminum" anilox. KNOW WHAT TYPES OF ANILOXES YOU HAVE! Finally,
when cleaning all bases and especially sleeves and aluminum rolls in heated
equipment, we do not recommend temperatures above 120°F (49°C.)
It bears repeating that Harper Corporation's first and foremost
concern with chemical cleaners is the health of one's employees. Typical health
and safety precautions require the use of safety glasses and rubber gloves when
using chemical cleaners.
Precautions should always be taken into consideration when choosing
a specific cleaning solution. More often than not, a roll can be damaged
because of the pH of the chemical solution. The typical pH of water based inks
is between 8.5 and 9.4. When cleaning water based inks or solvent based inks,
the pH of the chemical cleaner should never be below 5.5 (for carbon fiber
sleeves not below 6.5 pH) and never be above 11.8 pH. All cleaning chemicals
must be specifically formulated for ceramic anilox rollers. Although extremely
effective, ink cleaners outside this pH range are not anilox safe and can
damage ceramics and the engraving. Corrosiveness of a cleaner is no guarantee
it will work to clean up your particular ink system. It will require some
experimentation to find a health-safe solution and an anilox safe and effective
cleaner. Furthermore, most water based ink companies state that "pH" only needs
to be 2 points higher than the ink to rewet, so there is no need to use high or
low pH cleaners. When in doubt consult our Harper GraphicSolutions
professionals with your specific questions.
To summarize, Harper Corporation recognizes the many
variables associated with the use of chemical cleaners and has developed
stringent criteria involving the application. Successful chemical cleaning
should be considered a science rather than just a maintenance procedure. Work
closely with your suppliers in this area. We have developed our own chemical
cleaner(s) to give us as well as the customer the satisfaction of knowing what
they are using is safe.
Should you have any questions or need further information, please
do not hesitate to call Harper's Technical Services at (800) 438-3111.
July 2007
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