Densitometer for processless plates

Gianni_S

Well-known member
Hi all,
could you help me to clear out my ideas about this topic?
Which is the right device to measure (and linearize) processless plates (e.g. Fuji Pro-T, kodak Sonora Xp, and so on).
I was looking at Techkon spectroplate (full optional), but I've teste on of a collegue and… it doesn't work.
X-rite offers ICPLate2 XT that seems to be quite good… but a technician says that's the worst device he ever had to deal with.
At the moment I am a little bit confused. I think that's impossible to have such plates and no devices to read them.
What is your opinion and what do you suggest?

Thanx a lot!
 

arossetti

Well-known member
I asked our Fuji rep for a SOP on reading their process-less plates; I never got a response. Hope that helps.
 

gordo

Well-known member
Hi all,
could you help me to clear out my ideas about this topic?
Which is the right device to measure (and linearize) processless plates (e.g. Fuji Pro-T, kodak Sonora Xp, and so on).
I was looking at Techkon spectroplate (full optional), but I've teste on of a collegue and… it doesn't work.
X-rite offers ICPLate2 XT that seems to be quite good… but a technician says that's the worst device he ever had to deal with.
At the moment I am a little bit confused. I think that's impossible to have such plates and no devices to read them.
What is your opinion and what do you suggest?

Thanx a lot!

You don't need to linearize your plates. You don't need to measure them to build a curve. Just build a dot gain compensation curve based on file input and presswork.
 

arossetti

Well-known member
You don't need to linearize your plates. You don't need to measure them to build a curve. Just build a dot gain compensation curve based on file input and presswork.

With that being said Gordo; in 2 years when you notice an issue in the presswork how do you decide if it is CTP or press? That has always been my question.
 

gordo

Well-known member
With that being said Gordo; in 2 years when you notice an issue in the presswork how do you decide if it is CTP or press? That has always been my question.

Well, if it took you two years to notice there was an issue in the presswork you've got bigger problems than measuring plates.
Processless plates remove one of the major variables in print production - the plate processor. Basic production monitoring will tell you if an issue is press, plate, or imaging related. In any case, the OP's question was about measuring and linearizing processless plates - neither of which is needed.
 

Gianni_S

Well-known member
That's an interesting point of view, thanks a lot Gordo.
Now may I ask which instrument to use? X-rite, Techkon, else?
 

Gianni_S

Well-known member
Gordo, building a compensation curve means that you have to do it for every single paper, every press.
It could have sense, but with multiple substrate and multiple presses… well, this leave me a little bit scared by the enormous number of curves I need.
 

gordo

Well-known member
Gordo, building a compensation curve means that you have to do it for every single paper, every press.
It could have sense, but with multiple substrate and multiple presses… well, this leave me a little bit scared by the enormous number of curves I need.

No. Typically an average is taken of the shop's presses and a curve is built for that.
Many (most?) shops use that one curve for all their substrates.
Some shops will have two curves - one for gloss coated and one for uncoated book.

So, in most cases, you end up with only one or two curves.

To your other point I don't promote specific brands. If you're looking for a plate reader then most work basically the same. They take a greyscale image of the plate and apply a threshold to determine the edge of the printing dot from the non-printing background. So you need to test the device to see if it can distinguish dot from not on the plates you are interested in. You also need to see what other analysis the reader can provide (e.g. frequency, angle, etc.) You can get sample plates from the main plate suppliers as well as test instruments from Techkon, X-Rite et.al.. The instruments may be attached to a salesman dongle ;-)

As always, consistency is more important than absolute accuracy (a non-working analog clock reports the time accurately twice a day).
 
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arossetti

Well-known member
Well, if it took you two years to notice there was an issue in the presswork you've got bigger problems than measuring plates.

I don't think I was clear before; my point was if everything is running fine but then two years later a change happens it is harder to tell if it is the plate, CTP, or press if you cannot measure the plate.
 

gordo

Well-known member
I don't think I was clear before; my point was if everything is running fine but then two years later a change happens it is harder to tell if it is the plate, CTP, or press if you cannot measure the plate.

I would disagree - but I guess it depends on the shop's level of process monitoring and QC systems. If the shop doesn't have any QC programs in place then being able to measure the plate means that prepress can at least blame the pressroom if something goes sideways. :p But that's not the way I think a shop should run.
 
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Gianni_S

Well-known member
May be my point of view is outdated, but…
Having only a TVI curve to match standard in press ties up strictly a ctp and a press machine.
The problem is when you have to provide plates without knowing what kind of machine will print the job.
For that reason I find the "one curve" solution not so effective.
However it seems the only way with processless plates… unless someone pull the rabbit out the hat with a device capable of reading that kind of plate. (let me dream!!!).
 

ljgoldberg

Active member
All image-based plate reading instruments use visible light (400 - 700nm) sources and roughly equivalent imaging sensors.
If YOU cannot readily see the image of the halftone, neither can the instrument.
They cannot measure what they cannot "see".


Decades ago Agfa released a plate with a nearly invisible image.
Complaints from pressman caused them to pull the plate from the market and reformulate it with a benign dye in the coating, making the plate measurable with the popular instruments.

I prefer the Beta UltraDottie line shown here;
http://betascreen.com/Products/ctp/ultradottie2.html

Try it on the Free Ten Day Trial and report back.

Larry Goldberg
Technical Director
Beta Industries
 

Repro_Pro

Well-known member
For measurement purposes, I believe it is not too difficult, on most Process Less plates, to remove/clean the Non Image area after the plate is exposed.
The contrast between the Printing and Non-Printing areas will get enhanced enough for viewing as well as for measurement by most plate readers.
 

Alois Senefelder

Well-known member
Good God !!!!


Just run a random plate through a plate processor............. OR - Wash one out in the Sink, result you have a "Visible Imaged Plate "


Regards, Alois
 

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