Fountain concentrates, etchs, and gum wet the plate and serve to maintain that all important moisture barrior at the plate which controls where ink is attracted and rejected.
If you use a strong loupe to study ink patches printed with different wetting solutions at varing concentrations, you will notice a significant variation in ink density as a result of sheet show-thru caused by the small voids in the ink and water emulsion that allows the stock to show-tru the ink patch.
As a rule, the greater the concentration of fountain concentrate, the greater the void size.
In addition to sheet show-thru, high concentrations of fountain additives retard ink drying.
NULLThe surface hardness of ink oscillators is not that important but surface finish is.
Over time, hard ink oscillators develope a polished glazed surface that has little to do with dried ink pigments, its from the physical polishing action of the fine clays from paper coatings, dirt, and various ink pigments that act as lapping compound.
When hard ink rollers, both idlers and oscillators, become too smooth, they carry a thinner ink film than does the mating soft rolls creating an ‘ink transfer barrier’ that seriously affects the inks ability to flow uniformly thru the inking system.
KIINew.bmpThe Kompac’s Kolormate Oscillator roll serves a very important function by smoothing and redistributing ink build-up that accumulates on form roll when excess ink is picked up if plate is over-inked.
Without it, jobs with heavy ink coverage on one side would cause ink piling/rings on form roll which would then emulsify, disrupting moisture/ink balance to plate degrating print quality creating production losses.
If your Kompac’s Kolormate is positioned ‘on top’ of the form roll, it’s nip pressure should be set at a light 1/8″ inch on Kompac IIs and 3/16″ on Kompac IIIs to allow excess plate moisture to return back ‘under’ the Kolormate into Kompac for re-metering.
If your Kompac’s Kolormate is positioned ‘below’ form roll, after the metering nip, the same pressure requirement applies, but instead of running too wet, Kompac will run too ‘dry’ from lack of moisture.
The Kolormate’s nip pressure is produced/adjusted by pressure from set-screws at each end on some models and a compression spring with an adjustment screw thru it on others.
To check your Kolormate’s nip setting.
With Kompac inked, let Kompac set at rest for a few seconds to allow an impression to be made in the inked surface of the form, then briskly rotate kompac rollers for a short 1″ of travel and stop then closely observe the latent ink impression/stripe left on form roll’s surface from pressure of Kolormate.
If nip impression line is greater than stated above, reduce it.