Consiistent-excessive dot gain/TVI on all units.

[gordo]

Hi Gordo
I would very much like to get a scope, but after years dealing with all the bull in digital camera marketing, I can't find a microscope that doesn't confuse magnification with zoom, digital with optical magnification, focal area with distance etc.
Can you recommend one that will do the job right?

Thanks for any help.

This is the kind you're looking for: http://tinyurl.com/z257pk6

You need 20x - about 200x and if possible 2mp

The same gizmo is sold under many brand names at a wide variety of prices. They are all very good for analyzing, documenting and/or communicating presswork issues and they are inexpensive so there's no reason not to have at least one for QC use.

 

[CClyde]

Thanks gordo
I'll follow up with some shots when it's in.

 

[CClyde]

Is there anyone in the Toronto area with a good scope I can rent for a day? I've ordered the XCSOURCE 20X-800X 8 LED USB 3D Digital Zoom Microscope Endoscope Magnifier PC
and just discovered it's on a slow boat from China and may not arrive until mid September.

 

[cementary]

As we're still waiting for supplier's official answer to our BIG question about exessive dot gain and distorted dot shape, i've been thinking about ink and formed a speculation, which i'd like to share with you (and i'd like to summon any ink guys on this forum to this thread)

One night, when the moon was rising, i've been drinking another beer and came over one thought – some time ago the dot gain with same ink was ok. A little chronology just for stating the points:

1. In the year 2010 we've been compensating around 3 to 5 percent in 50 percent patch.
2. Then, around 2013 our suppliers started to exessively marketing uv-inks.
3. Around late 2015 we've started to compensate around 11 to 15 percent in 50 percent patch.

What do i know about the uv-inks? They are extremely water-receptive, it is really hard to maintain ink/water balance with them, as many threads on this forum and other forums confirms.
What do i know about water-receptivity? It is the characteristic of the binder (varnish to be exact) of the particular ink.
What do i know about big international corporations? They always looking to cut down expenses.

This was preface, now the speculation itself:
What if once upon a time big ink vendors put all stakes on uv-ink/led-ink technology and decide to cut expenses for number of different hard resins, alkyd resins (vegetable oils) and solvents (thinners). So all three to be the same for all ink products in their catalogue – both for uv and conventional. They've saved some money, and increased dot gain was referred to curve control problems in particular printing shops. The printers started to engage G7/PSO experts or just plain guys with spectrophotometers to create a brand new curve, so these guys earned some money too.
So today everybody happy.
Except printers.
'cause curve control can not predict differences in water-pickup in different situation with different ink coverage/sheet size/press run speed/temperature/pressman mood etc.
And the whole industry slips slightly into situation when printing became and art once again.

 

[gordo]

And the whole industry slips slightly into situation when printing became and art once again.

I have to disagree. This thread, and its posts, tells me that it was "art" that got the OP into trouble in the first place. It also showed that throwing "art" at the problem to try and solve it was not effective.
Most printers are not schooled in process control or scientific methodology (despite the efforts of their elementary school teachers) so they are often at a loss to know how to go about setting up a proper deterministic print manufacturing process. Nor to they have a systematic approach to resolving issues when they arise.
"Art" should be fired from the manufacturing departments.

 

[gordo]

Science just called, he was looking for a guy called 'Craft'. Anyone seen him around lately?

He's at the local microbrewery.

 

[cementary]

Nor to they have a systematic approach to resolving issues when they arise.

Don't you see any systematic approach in step-by-step excluding / checking and re-cheking factors and which affects dot gain on the press?
Under the "art" i actually meant sid adjustments on press – the only thing left for pressman to get a closest match to the proof.
So who shoud be fired in the first place – all the pressmen?

 

[CClyde]

I have to disagree. This thread, and its posts, tells me that it was "art" that got the OP into trouble in the first place. It also showed that throwing "art" at the problem to try and solve it was not effective.
Most printers are not schooled in process control or scientific methodology (despite the efforts of their elementary school teachers) so they are often at a loss to know how to go about setting up a proper deterministic print manufacturing process. Nor to they have a systematic approach to resolving issues when they arise.
"Art" should be fired from the manufacturing departments.

Interesting, very interesting.

Although I've spent 25+ years in prepress and a lifetime trying to get people to understand some of the most fundamental principles of deduction, this is the first time I've been personally/physically involved in solving a specific problem on press.

I am presently trying to explain and persuade management of the need, value and ROI of "process controls".

Process control, management, documentation and analysis all sound like marketing hyperbole to most traditional printers. "This is the way we've always done it!". "Have you ever run a press?". "We have estimating programs that do that." etc., etc.

There is no point in arguing, "A man convinced against his will, is of the same opinion still."

The only way traditional printers will accept and benefit from process control is to put it into practice and let them see/measure the results.

Going home everyday at the end of a productive shift, producing work they can be truly proud of is just one huge, collateral benefit of process controls for press operators and management.

Without process controls in place, every problem becomes a chaotic "cat herding" event that inevitably ends in bandaid fixes, tempers flaring and discouraged employees and customers.

Don't get me wrong, we have great press operators who pull rabbits out of hats, but they are getting really tired and fed up of being the star attraction in a dysfunctional circus.

If I can get management to let me implement process controls the circus will be back in town with smiles on every face and free candy floss for everyone.

 

[curiosity]

I have a suggestion for implementing process controls.....begin very small, correct something, anything and once accepted as a solution, go about showing how you did it. Worked for me. And I've got countless stories to back it up.
That said, total implementation will likely be miles away. I'm certainly not there, and may never be. Anyway, one small correction/improvement, perhaps one pressmen/supervisor/manager at a time... it's a good place to start.

 

[gordo]

Don't you see any systematic approach in step-by-step excluding / checking and re-cheking factors and which affects dot gain on the press?
Under the "art" i actually meant sid adjustments on press – the only thing left for pressman to get a closest match to the proof.
So who shoud be fired in the first place – all the pressmen?

Read CClyde's recent post.

"Art" can be an effective way of dealing with non-deterministic processes - like hitting a baseball or golfball to reach your goal.

But art is not the most effective way to deal with deterministic processes like 2+2=? or a printing press.

"Deterministic" is a physics (and philosophical) term. In this context I'm using the term to mean that if the initial state were known exactly, then the future state of such a system could theoretically be predicted. I.e. if you know what goes in you can predict what comes out. Conversely, if you know what came out you can determine what went in. A deterministic system is a system in which no randomness is involved in the development of future states of the system. A deterministic model will thus always produce the same output from a given starting condition or initial state.

That is not the approach that seemed to me to be described in the OP and subsequent replies.

 

[gordo]

I have a suggestion for implementing process controls.....begin very small, correct something, anything and once accepted as a solution, go about showing how you did it. Worked for me. And I've got countless stories to back it up.
That said, total implementation will likely be miles away. I'm certainly not there, and may never be. Anyway, one small correction/improvement, perhaps one pressmen/supervisor/manager at a time... it's a good place to start.

I would agree with that.
For management to buy in to any change in the process there typically needs to be a demonstrable ROI - usually monetary in some form (actual dollars, more profit, less cost, etc.)
For worker bees there is seldom a direct benefit connection to making any changes - so there's little incentive to making a change. Indeed, some worker bees would (knowingly or unknowingly) sabotage any possible benefits to making any changes since the value of their ability to fix problems/disasters that arise in daily production would be diminished.

Can you tell I'm feeling cynical today LOL!

 

[CClyde]

I have a suggestion for implementing process controls.....begin very small, correct something, anything and once accepted as a solution, go about showing how you did it. Worked for me. And I've got countless stories to back it up.
That said, total implementation will likely be miles away. I'm certainly not there, and may never be. Anyway, one small correction/improvement, perhaps one pressmen/supervisor/manager at a time... it's a good place to start.

Good point.


I've demonstrated a number of simple yet profitable processes that while appreciated in and of themselves, are not understood as demonstrating the systemic/endemic problems of much larger and costlier nature.

As gordo mentioned, there are some here who fear their value to the company is directly proportional to their control of the artistry, which they demonstrate in their ability to solve problems. Problems that in most, if not all cases only exist because their methods are artistic.




I too am a little cynical today.

 

[CClyde]

Got the scope about an hour ago. Struggling with focus, but thought I'd post what I have so far.

 

[Prepper]

Good point.


I've demonstrated a number of simple yet profitable processes that while appreciated in and of themselves, are not understood as demonstrating the systemic/endemic problems of much larger and costlier nature.

As gordo mentioned, there are some here who fear their value to the company is directly proportional to their control of the artistry, which they demonstrate in their ability to solve problems. Problems that in most, if not all cases only exist because their methods are artistic.




I too am a little cynical today.

Not so much cynical as just the way it is. I wouldn't have so much of a problem with art or craft IF some ability was demonstrated to solve problems, instead of just requesting me to adjust curves to make it work for them continually! Otherwise it's just asked how do we know which is right, the proof or the press, the plates or the press, never ending cycle of avoidance. I actually quit applying curves and just made linear plates for over 6 months and no one ever knew the difference. I removed HIGH GCR one time though and they really hollered then, that did prove to them how much it minimizes color shifts. But I cannot for the life of me convince them of the importance of SOP and trying to maintain the press in some sort of "baseline" condition. Oh shoot! I am too cynical also I guess.

 

[CClyde]

Just to clarify my cryptic labels;

Magenta 50% on plate is 60% tone value on print and 78% dot area.
In more traditional terms it means we have a 28% dot gain at 50.
This is one of the better runs.

 

[gordo]

Just to clarify my cryptic labels;

Magenta 50% on plate is 60% tone value on print and 78% dot area.
In more traditional terms it means we have a 28% dot gain at 50.
This is one of the better runs.

Woooot!

You posted low res pics of your dots and solids. Despite that, they look fine.

When you say: "Magenta 50% on plate is 60% tone value on print and 78% dot area."

No. If a 50% magenta on the plate results in a 60% tone value on print then you have 10% dot gain. In that case the 60% tone value on the print represents a 60% dot area. Tone value and dot area are the same thing - just different names because of different ways of charting the same data.

How do you get 78%?

BTW focus is difficult because of the shallow depth of field resulting from the high magnification. That's normal.

 

[cementary]

Read CClyde's recent post.

"Art" can be an effective way of dealing with non-deterministic processes - like hitting a baseball or golfball to reach your goal.

But art is not the most effective way to deal with deterministic processes like 2+2=? or a printing press.

"Deterministic" is a physics (and philosophical) term. In this context I'm using the term to mean that if the initial state were known exactly, then the future state of such a system could theoretically be predicted. I.e. if you know what goes in you can predict what comes out. Conversely, if you know what came out you can determine what went in. A deterministic system is a system in which no randomness is involved in the development of future states of the system. A deterministic model will thus always produce the same output from a given starting condition or initial state.

That is not the approach that seemed to me to be described in the OP and subsequent replies.

Gordo, i really do not see point for arguing. If there would be a call for SOP – i'd jump into that train in half a minute.
Maybe due to my bad english i didn't manage to explain that "art" i post before. So i'll try to state my opinion in non-ironic way:
Our supplier demand that adjustmentin SID on the press (within +/-0.25) is normal for industry and every printer work that way. That's their recommedation for us (and other printers, who work with them i suppose) to hit the proof. For different jobs – different adjustments.
This is what i meant under the word "art".
I do not think that this is ok.

And Gordo, with all due respect, what's your next post adressed to me will contain, multiplication table? LOL

 

[CClyde]

I don't know if I'm using the correct, or standard terms.




Here's the big picture as I understand it.

An artist fills a circle with 50% magenta. That tone is not represented on the artist's screen as a dot/halftone. The artist sees a solid circle with a tone value of 50% magenta.(RGB, Lab etc.)

The printer RIPs the artist's file (targeting a sheetfed, offset, gloss coated production) which translates the 50% magenta into a screen with a dot area of something less than 50% in order to compensate for dot gain.

The press operator prints the work to a target density such that the solid density of each dot and the resulting gain brings the artist's circle to a "visual" tone value of %50% on the sheet.

The sheet goes into a magazine where the reader sees the artist's circle as a 50% tone value.

The reader does not perceive the dots, or the ink density that, with the paper, together make up the visual perception of 50% magenta.

If the solid density of the magenta ink film on the sheet is more, or less than the target density, the 50% tone value can be achieved by a dot area greater or lessor than the target dot area.

So, although a 50% plate dot can be a 68% dot area on the sheet, it can have a tone value substantially more, or less than 68%.

 

[gordo]

Here's the big picture as I understand it.

An artist fills a circle with 50% magenta. That tone is not represented on the artist's screen as a dot/halftone. The artist sees a solid circle with a tone value of 50% magenta.(RGB, Lab etc.)

The tone they're seeing on their display is a 50% request represented as a tone according to the ICC profile that's being used to drive the display. It's not 50%.

The printer RIPs the artist's file (targeting a sheetfed, offset, gloss coated production) which translates the 50% magenta into a screen with a dot area of something less than 50% in order to compensate for dot gain.

OK

The press operator prints the work to a target density such that the solid density of each dot and the resulting gain brings the artist's circle to a "visual" tone value of %50% on the sheet.

No. The press operator prints the work to a target density. Dot gain will result in the 50% request in the file that resulted in - for example - a 46% on the plate to image a tone in the presswork that results in - for example - 68% on the press sheet. That 68% tone on the press sheet which resulted from a 50% request in the file will have a similar appearance to the 50% tone request in the file as displayed on the designer's computer display.

The sheet goes into a magazine where the reader sees the artist's circle as a 50% tone value.

No. If you measure that tone on the presswork it will report that the reader is seeing a 68% tone where a 50% tone was requested.

The reader does not perceive the dots, or the ink density that, with the paper,

Yess.

together make up the visual perception of 50% magenta.

together make up the visual perception of the 50% magenta requested in the file.

If the solid density of the magenta ink film on the sheet is more, or less than the target density, the 50% tone value can be achieved by a dot area greater or lessor than the target dot area.

No. If the solid density of the magenta ink film on the sheet is more, or less than the target density, the 50% tone value requested in the original file will not deliver the target tone value (e.g. 68%) for the requested tone.

So, although a 50% plate dot can be a 68% dot area on the sheet, it can have a tone value substantially more, or less than 68%.

That's confusing. You need to keep three things clearly separate. Target tone. Requested tone in the source file. Tone on plate that will deliver the target tone on press. Plate curve/dot gain compensation curves are predicated on this principle.

 

[ianmcc]

I think it could be a new resin in formulation. Or maybe any other "eco-nail" for printing industry coffin.
From my experience many companies don't care much because of high dot gain and especially because of deformed dot on printed sheet. The answer for them is "compensation curve"
All print shops with whom me or my colleagues talked to do not see any problem in their high dot gain and they do not have microscope to see their deformed dot.
One reason is because same supplier do not see problem too. They intend only to sell ink and don't care how it work. Technical support is very poor. Actually most of the support is lots of talking to convince us that problem is not in the ink or ink/fount pair.
Other reason is that printers are still able to sell their printed sheets to the customer – position is "why bother" consistency?

Just today we've finished another set of tests with manroland servicemen who cheked again all rollers/cylinders/pressures/bearers etc.
And we've test different inks – with one of the ink we've obtain acceptable result.
Test method was simple as we've tired printing charts: we've output a linear testfrom with 70% all over the plate (200 lpi, round dot, 0 degrees).

With our "bad" ink there were a lot of big horisontal lines over the sheet from head to tail – like form rollers gone made and trying to beat the plate to death. Dots were distorted with ragged edges. That's when we're undestand that fount cannot clean the spaces well enough (tested with lots of water levels)

With our "acceptable" ink there were no lines or distorted dots on the sheet at all. I've finally saw a sheet 70x100 full of clearly printed 70% dots right out of our press. And they all were round, not perfectly, but good enough for wet offset.

Hi Cementary,

I have just stumbled upon this discussion and cannot believe the similarities with what we have been dealing with for the last 4/5 months. What you are describing is exactly the same as we are encountering on a brand new Heidelberg XL106 press. Heidelberg have been in numerous times and checked the press from back to front and we have been doing exactly the same tests as you describe - a 70% 700x1000 sheet (200 and 175 lpi, elliptical dot)
We are seeing the exact same issues, banding, distorted dots, high dot gains,and poor quality screens.
We have been running the SID low to get a "cleaner" result.
These issues have been going on for months now, and we are exasperated - this discussion seems to strongly suggest the ink is to blame - we have already come round to this conclusion also. Can I ask what ink you are describing as your "acceptable" ink as that would be very helpful.

Thanks, Ian