A Few More Thoughts on Ink Mixing.....
The answer to the question of being able to physically mix and blend inks to
make PMS inks is yes. As pointed out in previous responses, there are several
different techniques (e.g., mixers and hand mixing) and software programs
available. The real issue is the economics associated with the activity.
Generally, it is only cost-effective for a printer to mix their own ink if
there is a sufficient volume of PMS inks used because the printer will have
to stock certain 'basic" mixing inks. Not all PMS shades can be mixed from
other inks. The printer will also have to pay someone to mix the inks and if
it is a press operator, this could be an expensive proposition. Generally,
unless the printer does a significant amount of PMS printing, it is more cost
effective to purchase these inks pre-mixed from the vendor.
With respect to mixing left over ink and making black ink, this is also
possible as some pritners are able to accomplish this. There are concerns
about the quality of the resultant mixed ink, and in the case of sheetfed
inks, removal of the skinned and dried fractons of the ink. Becasue sheetfed
inks dry by oxidative polymerization, the printer will be challenged with
keeping the skins and dried ink globules from interfering in the quality of
the remixed ink. Since globs of dried ink do not print well and the economic
factors associated with mixing used inks into black, most printers do not
undertake this activity. However, some larger printers have found that mixing
their own PMS inks and reblending fountain returns and unused inks into black
to be cost effective. The driving force is the economics of the activity.
Another inhibiting factor to remixing used inks is the regulations associated
with the activity. While EPA does not consider uncontaminated lithographic
inks to be classified as hazardous wastes, some states do consider them
hazardous. For example, the state of California lists offset litho inks as a
state hazardous waste. Other states that regulate used oil as a state
hazardous waste can regulated waste litho ink as hazardous. The concern with
regulating litho ink as hazardous is that any activity considered "treatment"
such as reblending used ink into PMS or black inks could be subject to
permitting. Therefore, any printer wishing to undetake this activity needs to
contact their state to see if they would be subject to permitting