Pressroom Matching to Proof Guide

[CKL]

I'm looking for input from the forum on how others communicate with the press room on color matching.
Proof to press match guidelines for them ?

Press guys will say close enough...
What's close enough ?
Should they measure Delta E between the proof and press in areas that do not match ?

Their standard press color-bar data would be saved by the press color scanner.

Thanks
CKL

 

[gordo]

Is this for commercial sheetfed or publication web or?

 

[CKL]

Commercial
Thanks Gordo

 

[gordo]

I'm looking for input from the forum on how others communicate with the press room on color matching.
Proof to press match guidelines for them ?

Press guys will say close enough...
What's close enough ?
Should they measure Delta E between the proof and press in areas that do not match ?

Their standard press colorbar data would be saved by the press color scanner.

OK, for commercial presswork...

Preamble....

It helps to not think of a printing press as making color but rather what it is basically designed to do: lay down an even film (about 1.5 microns thick) of ink onto a substrate in the presence of a film of solvent (fountain solution). That process is in flux and is affected by the image contents/ink usage, paper,, temperature, speed, etc.

The press operator's mind is primarily focussed on accomplishing that task rather than "matching" a proof. Delta E talk will likely not be understood.

"Matching" the proof...

Printing is an analog process rather than digital. It's not binary. So there are degrees of "match" ("close enough") once the press reaches it's nominal condition for the job. By their design, offset are stable - but not consistent while running a job. All that implies a tolerance for "match."

OK...

To your specific question.

IMHO, ISO 12657/GRACoL 7 primarily relate to setting up a press to align to an industry specified print characteristic that is embodied by a proof that represents that print characteristic. The targets and tolerances specified are not necessarily reflective of real production printing. So, industry specified tolerances may end up too narrow or too wide for any given production job.
The color bar on a live job may not reflect the appearance of the live image area ("we sell the job's appearance not the colorbars"). They can be useful as base targets for reprints though.
There is also no industry specified tolerance for the live image area. System Brunner tried to create such a system (the Star rating system) back in the 70s - but I don't think that it ever really caught on.

So, what usually happens is that the press operator "comes up to color" during make ready and ends up with presswork that, in his opinion and given the time and materials constraints he's operating under, aligns enough to the proof in terms of overall visual appearance that most buyers (or their representatives) will accept it, pay for it, and not demand a reprint.

For jobs that are more critical in terms of press to proof alignment, the information about what elements of the imagery needs the closest match and which elements of the imagery that can be sacrificed in order to make the match are communicated by the sales rep to the pressroom or by the print buyer directly. Then, during makeready, the press operator comes up to color then tears/cuts a press sheet through the critical color area and lays it over that area on the proof. If he cannot visually distinguish between the the press sheet and the proof at the crossover then he's made the match and runs the job. Generally, for this type of work the print buyer and/or their representative will be available press side or in a customer recovery room to confirm agreement (or disagreement) with the press operator's judgement.

This is all done visually rather than by instrument because while instruments may provide a numeric indication of a match the numbers may not correctly indicate the actual appearance of the match.

Some related reading on the topic:

Who is responsible for print shop color?:
The Print Guide: Who is responsible for print shop color?

What the press operator is scrutinizing:
The Print Guide: What the press operator is scrutinizing

The Color Bar:
The Print Guide: The Color Bar

 

[chevalier]

Gordo nailed it as I suspected that he would.

Running "to the numbers" and then visually verifying that what the numbers are telling you is a match has become our SOP. If they don't match you do your best to find the cause within reasonable limits and resolve it. I work in cartons now but I used to work in commercial so I got to see two similar but different worlds' perspective on this. To make all of it "match" you have to have strict and tight controls in multiple places.

Control point one: Design / Preflight
Files have to be designed/preflighted in reasonably correct color space(s) or converted to destination. Common example: Customer designs for SWOP and your printing in GRACoL. Either you honor the CMYK values used and discard the SWOP profiles or you convert to destination. This takes expertise to make the right decisions.

Control point two: Proofing
Proofers must be calibrated to the actual desired standard. A proofer calibrated to SWOP won't do you any good if your printing to GRACoL. If you are commercial you really should have multiple proofing profiles for different conditions and stocks. The beauty of these proofers is that they can reasonably simulate various stocks. The stock that is going to be utilized in production should dictate the preflight profile(s) utilized AND the proofing calibration profile(s) utilized.

Control point three: Plating
Your plates must be consistently imaged and developed. If you have multiple CtP devices they should all be linearized. You should be verifying this at minimum once a month (after each cleaning cycle). A further CMYK dot gain compensation profile should be calculated for each press. These profiles are not interchangeable just because you have two SM102 presses.

Control point four: Printing
The printing press must be maintained for wear and tear and/or^ the plating profiles updated at regular intervals or when a major change of behavior occurs on the press.
^This really should be an AND

Summary
The proof has to reflect what is going to be printed within "reasonable" tolerances. CMYK is under control on our few substrates and we have the ability to directly proof onto our press stocks with a Fujifilm FinalProof. We can simulate them on our inkjet proofer as well. If your proof is simulating a "#1 sheet" and your printing on a "#3 sheet" your not likely going to match but you could possibly "ball park" it. To accurately proof you need to setup simulation profiles and realistic color controls on the front end of prepress.

Customer Approvals
When customer's come in for a press approval it becomes a whole other thing altogether. That thing is best described as a "cluster#$*" as they usually bring in some sample from some printer from some time ago with no measurable color strips of calibration info. The proof goes out the window other than for copy and a joint effort between the press room and prepress is established. We work very hard to prevent this from happening but....

Closing the loop for repeat production can become a huge headache. Our rule is to complete the run after make ready approval unless the press has been put into a precarious state to satisfy the customer*. If a repeat order is expected** the artwork is then immediately re-preflighted and color corrected and new proofs produced to standard are generated until the proofs are a visual match and a copy match by prepress and the pressroom manager. That proof and the signed off sheet from the press approval become the new proof. The press sheet has an expiration date assigned due to yellowing, etc. Typically it will be archived or tossed after the 2nd or 3rd run.
*If the press is in a precarious state we will stop and perform the procedures above.
**If a repeat order is not expected the proofs are flagged and if a reorder occurs we perform the procedure above.

Pantone, Toyo and other Special match colors
These companies make it very clear that their ink formulas are NOT designed to be screened. How they will screen is almost unpredictable. There remains debate as to whether the press room should match the solid ink and let the screens do what they will or whether the pressroom should try to achieve a solid ink match AND a visual screen match. I'm with concept one and willing to generate job specific curve data and replate if needed. We verify spot colors on our proofs for solids but for screens this does't work at all as you have nothing to target to.

I'm tired! Hopefully no glaring oversights or oversimplifications.

 

[CKL]

I really appreciate you guys taking the time.


Thoughts on color bars with & without AQ ?
High Gloss, Gloss, Satin, Matte.


The customer & sales may not understand matching to the color proof can be difficult when the job spec's are Matte AQ on a Dull sheet.
They will tell the operator running over the weekend "we need more pop".

It seems like I am running into less experienced buyers and lack the tools to communicate properly.

Cheers
CKL

 

[chevalier]

I really appreciate you guys taking the time.

The more vocal people dealing with this day in and day out are the more other printers will adapt and buyers will have to learn how to communicate properly. I've been told I am naive about this but I remain optimistic which is why I spend some free time here on print planet. I encourage anyone to do this. I know there are a lot of lurkers out there so, CONTRIBUTE! I've actually been in a meeting once where someone printed off my post from printplanet to back up their claims to me!

Thoughts on color bars with & without AQ ?
High Gloss, Gloss, Satin, Matte.

Color bars should always be given the same treatment as the rest of the sheet. It's important to know that some coatings have OBAs in them - especially AQ matte coatings - which can through off measurement data if the proper measurement conditions are not set.

The customer & sales may not understand matching to the color proof can be difficult when the job spec's are Matte AQ on a Dull sheet.
They will tell the operator running over the weekend "we need more pop".

This can somewhat be covered by proofing on a material that is similar to the actual press stock rather than just having one single proofing paper. Additionally see my comments above about simulation profiles and standard profiles for various stocks and conditions. Stocking an additional roll or two of $300 proofing paper shouldn't break the bank of any printer that's quality conscious and has customers paying for quality.

It seems like I am running into less experienced buyers and lack the tools to communicate properly.

You and everyone else. "Quality" in the general sense has kind of become a given assumption and the buyer wants to buy the lowest price. I worked hard in a previous life (with some minor success) to educate buyers and designers. We had monthly seminars where'd I'd explain some topic, provide handouts and give free catered lunches.

Time for a rant...
One of the biggest hurdles that I regularly come across is related to coatings.

Customers many times want proofs that reflect dual matte and gloss UV coatings but also want accurate color. Such a proofing device does not yet exist and they definitely don't want to pay for a press approval. I've currently got an open proposal to buy a Versacamm LEC and use it only for apply coatings on top of FinalProofs. None of these customers seem to want to pay for it though.

Customers also want to just say "gloss" or "satin" and then complain when product isn't as glossy or dull as they wanted. I pushed hard to our marketing and sales people to put together some printed materials showing various coating techniques with gloss values. Then they would market coatings as a gloss value and not as "UV", "AQ", "satin", "matte", "gloss", etc. It flopped and I was told the customers did not want a science lesson in reflectance and gloss meters. Yet somehow they see it fit to complain when they ineffectively communicate what they want. Nobody is going to say "Blue" they're going to say Pantone 312 or Pantone 286, KURZ 375 or KURZ 326 yet coatings do not get the same treatment.

 

[gordo]

The customer & sales may not understand matching to the color proof can be difficult when the job spec's are Matte AQ on a Dull sheet.
They will tell the operator running over the weekend "we need more pop".

It seems like I am running into less experienced buyers and lack the tools to communicate properly.

Cheers
CKL

Every staff member that dialogs with customers should have access to a demo kit that shows representative samples of proofs to press matches on various substrates and coatings. You don't have to explain the science of why things look the way they do - what's important is that you set the correct expectations in the customer's mind. The kit is also a great place to store examples of PMS colors that shift when coated or laminated, or fade in a short time as well as any examples of things learned press-wise that might help customers and personnel.
In this case, showing is more effective than talking.