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- The premise used for many of your arguments, is that the ITB configuration somehow has a greater influence on the downstream ink train. In other words, why should the ITB configuration have any greater influence on the downstream portion of the ink train than a more conventional inking system does?
- Regarding the press interval. I would argue that the first down ink's TAC has a stronger correlation with the press' speed and thereby the press' interval which determines the length of time that the paper's capillary force has to act and increase the effective TAC of the first down ink, with respect to the second down ink.
I fail to see how the ITB technology influences the paper's capillary force during the press interval and resultant TAC increases to a greater degree than a more conventional inking system does?
Best Regards
OtherThoughts
Other Thoughts, yes this is an old thread. But OK, I will try to comment.
1. The ITB has more influence on the down stream portion of the roller train than conventional because it is positive ink feed. This is not an instantaneous influence but an average influence. On the other hand with a non positive ink feed as with the conventional system, the conditions can drift at the down stream parts of the roller train. What is being influenced is the mass flow of ink.
2. The second question is similar to the faulty view that is common even in the research areas of printing. It is the fault of linking the surface interaction of the ink and paper with the total ink transfer. Many of these studies of ink transfer are static or dynamic but without constant ink feed.
Yes, one can argue that there are properties of the ink and paper that initially affect ink transfer but after the printing process reaches a equilibrium or a steady state condition, the amount of ink transfer is directly related to the ink feed. At that time, it is not related to the interfacial properties of the ink and paper.
If the ink feed is inconsistent then the ink transfer will be inconsistent. If the ink feed is consistent, then the ink transfer, on average, will be consistent.
So no matter what the paper and ink properties are or the roller settings are (as long as they are in contact and transfer ink) the total ink transfer will equal the ink feed on average. The problem with conventional inkers is that changes in those conditions affect the ink on the roller train and this affect moves up to the ductor and then affect the ink transfer into the press and causes inconsistent ink feed.
With overprinting, if all the second down solid print goes on the first down print, then the ink transfer of the second down print is not affected by the changes in tack of the first down print. As I have said in an earlier post, if some print of the second down print is overprinting and some is printing directly on the paper, then there might be some small differences.
Those differences would be there for conventional too. The interesting thing about a positive ink feed is that there is the potential of doing something about where the second down ink goes. If the second down ink has more water added, the total volume of ink does not change but there may be an affect on how much ink is being wet trapped onto the first down ink. It would be interesting to see if this is a viable condition.
Conclusion.
I don't understand why an industry prefers a non consistent method of controlling an important variable than having a low cost consistent method. I don't know of any other industry that would view things that way.
Also I don't understand why there is so much effort in trying to find something wrong with a more consistent ink feed approach than there is in just having the concept tested by an independent third party to prove what's true.
I don't understand why an industry that claims it wants to be more scientific, does not want to think about these things. Right now the industry has no explanation why density changes on press that makes any sense.
It is understandable that people can be skeptical but that just means that there should be an interest to find what is true.
After 12 years of trying to explain this potential to the industry, I am getting kind of tired of having to repeat myself about something that should be quite obvious once it is described.