Re: Ink Saving solution?
"The ink savings comes from the cut back curves allowing for the final perimeter, or desired tone value increase. "
Well I guess in a way it does. If there is more dot gain with a particular screen type, then the physical dot size would not have to be so big and therefore less ink.
But I think there is a more fundamental reason for ink savings with FM screening and maybe the concentric screening. It has to do with how much ink the image on the plate will take from the form rollers. I briefly commented on this in my 1997 TAGA paper.
The idea has to do with ink film splitting between the plate surface and the form roller surface.
Let's think of a large solid. Normally one assumes the splitting to be 50%-50%. The ink splits and half of the ink film goes to the plate and half stays on the form roller surface. Pretty simple concept.
Now let's think of dots on the plate. Dots are not continuous and their affect on how much ink actually goes to the plate is now more complicated because there is an opportunity for ink to flow laterally. It might even be possible that mid tone AM dots of lower lpi values, could have more ink on the plate dot than the 50% spit situation due to the lateral flow. Fluid mechanics is complicated.
One the other hand, if we talk about very very small dots, one would not expect that a very small dot would be able to pull off a 50% ink film from the form roller. The smaller the dot, the less ink it would be able to pull off the form roller relative to its dot area.
As a side note, this phenomena of less ink consumption affects ink estimation and ink key presetting.
It is clear that if you know that a particular screen uses less ink, then one can estimate ink consumption.
With ink key presetting, there is some confusion in the industry. Some ink key presetting products claim to compensate for dot gain. This unfortunately is an erroneous claim since dot gain is not directly related to ink consumption. Bad science but good marketing.
Some ink key presetting systems also claim to have self learning capabilities. This is also erroneous since each new print design can result in a new set of variables that affect ink consumption. Screen size is just one of many factors. Bad science but good marketing.
Mathematically, a self learning system is not possible becasue each set up could be like having a new set of simultaneous equations to solve. It can be solved if one knows the equations but it can not be solved by a self learning system because the set of equations would change on the very next set up.
