FM Screening for the Newspaper

nilay

Active member
How the violet CtP system (Agfa Avalon) work for the FM screening for the newspaper ? Any newspaper in United states applied FM screening with Violet CtP system ?

Thanks in advance for helping me out.
 
Re: FM Screening for the Newspaper

Nilay,
I'm running FM on newsprint everyday. We run thermal plates, but the screening is really not that fine. We're running 31 micron on coated stocks and 42 on newsprint. Those equate to around a 15% dot at 175 lpi. I would think that ANY plate should be able to do that!

The next question is about durability. I don't have a clue about the durability of violet plates. We haven't noted any adverse durability issues in having moved to stochastic screening.
 
Re: FM Screening for the Newspaper

I remember Niko Ruokosuo did a paper on FM for newspaper, which I think was published by IFRA many years ago. That at least seemed to show that there should be printing quality advantages printing using FM screening on newsprint. One of the arguments was that it could achieve a comparable image resolution using lower resolution images, but I think that argument is sensless nowadays with current RIP and network speeds.
Regarding the plate technology, violet or thermal. High-volume newspaper CTP users tend to use photopolymer plates in the main. Most high-end newspaper systems tend to be violet; a) for the speed, and b) for the plate performance in coldset newspaper printing. "Thermal newspaper" CTP plates are actually also photopolymer plates, but they have just been sensitised to the alternative wavelength. Violet plates only need about 50 micro Joules/sq cm, whereas thermal newspaper plates need 120 milli Joules/sq cm; so for the same speed performance thermal systems need more laser power/more exposing channels, ie more lasers.
True thermal plates do not have such a good run life under coldset newspaper conditions as photopolymer violet or photopolymer thermal plates (but there may be exceptions to the rule!)
Having said all that I don't think there is any plate-technology related issue that would prevent either violet or thermal newspaper (photopolymer) plates being used for FM screening. As another reply has said, you wouldn' t be using ultra-fine microdot FM to print on rough news stock, you would be using 32 or 42 micron dots. Those equate to quite large conventional screen dots, so undue dot sharpening shouldn't be an issue. Although 42 micron dot is easy to print, being relatively large it has to be rather spaced out in highlight areas (resulting in a granular result that probably won't be preferred over AM screening).
I think the reason why newspapers have shied back from FM, is that
a) FM screening will more readily show-up any exposing or developing imperfection in your system; b) FM screening is more prone to "piling" in the press than AM screening, prehaps requiring more press stops in a long print run; and c) FM screening has a different dot-gain characteristic, which needs to be profiled or calibrated for.
Whether violet or thermal, it doesn't make any difference.
regards,
Barry
 
Re: FM Screening for the Newspaper

Hi,

Kodak has many newspaper and insert customers running Staccato (FM) screening - all using thermal (we had samples from about 20 customers on display at Nexpo earlier this year). I'm not aware of any newspaper/insert printers running FM with violet CtP. There are certainly differences in CtP imaging process consistency between violet and thermal (and Kodak thermal) that would make violet problematic for very fine screens whether AM or FM (as alluded to by Barry's point A). FM screening is NOT more prone to piling than AM screening (this has been verified in tests conducted by PIA/GATF) Piling results when ink/water balance and formulation is not appropriate for the fine/high lpi screen being used - AM or FM. If this issue occurs - it is a straight forward process to solve it.


best, gordo
 
Re: FM Screening for the Newspaper

Thanks a lot for your quick replies.

I worked with FM screening with Thermal CtP system but not with Violet CtP (we have Agfa Avalon). My assumption is that, if you optimize the CtP workflow (1x1 checkerboard pattern and evenness of the plate), there should be the least problem in printing. Here I have now quick question. Ink film thickness on the cylinder should be low for FM screening then the AM screening. Is that helpful to keep fount soultion preset low and eventually newsprint absorb less fount solution and low fan out for registration? Could it be helpful to mininize the scumming problem (with better ink and fount solution relation) and better registration as fanout should be less ?
 
Re: FM Screening for the Newspaper

Gordon:

Although you may not be familiar with Violet FM use in newspapers,
I'm sure you acknowledge, as Barry suggested, that violet and photo-
polymer is the standard when it comes to high volume production...

<snip>
With the two new :polaris engines, The New York Times Company now has 25 Agfa CtP systems, effectively positioning Agfa as the standard-bearer for computer-to-plate imaging technology for daily newspapers.
<snip>

Since the lion's share of violet systems are Agfa, for those who
desire high-line screening, they'd be using Sublima. At a web
offset meeting Gannett told of three sites - one Sublima, one
Staccatto and one Sandy Screens. Of the three, the Sublima
site (El Paso) had the fastest implementation, the fastest
attaining proper profiling, the fastest to gain mind share in
the pressroom, and the fastest to gain advertiser approval.
One key issue, especially in newspapers (or at least it was
for this trial), was the issue of managing dot gain with FM on
newsprint.

So.... most high-volume newspapers run violet photopolymer;
most violet photopolymer installations are Agfa; ergo, most high-
line violet screening would be Sublima, not FM.

Regards,

Edited by: Steve Musselman on Jul 16, 2008 7:54 AM
 
Re: FM Screening for the Newspaper

Steve,

As I'm sure you know, Kodak Maxtone screening is functionally equivalent to :Sublima - the key difference being that Maxtone screening enables the printer to fine tune the threshold dot size according to their specific needs. BTW, the ability for our customers to independently tune highlight, shadow, and midtone dot size and frequency to suit their prepress/press environment will also be available with Kodak Staccato (FM) screening with the release of Prinergy 5.
In any case, the original question was not about hybrid AM/XM screening, it was about Agfa violet FM. Specifically: "Any newspaper in United states applied FM screening with Violet CtP system ?"
Well are there?

thx, gordo

PS Nilay, I suggest that you work closely with your vendor (Agfa?) as they would be in the best position to know whether your plate and imaging system is capable of doing FM on a routine basis. They would also be able to draw on their customer base experiences with FM for newsprint and guide you with best, prepress and pressroom, practices information.
I could send you samples of inserts done by our customers as a reference to what some publishers are doing if you like. Just contact me off-line at gordon(dot)pritchard(at)kodak(dot)com and provide me with a physical address to send to.

Edited by: Gordon Pritchard on Jul 16, 2008 4:02 PM
 

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