GLGA Member Question – Press Color Okays

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QUESTION:
With the numerous list of print variables, press conditions and running equipment between locations we can see variations between color okays on the initial color okay and repeat runs. We are looking for feedback / best practices for press color okay’s specifically on repeat jobs.

  • What information do you document on your color okay’s ?
  • What do you reference to on repeat runs: the last run color okay? or original color okay ? the original pre-press proof ?
  • (Litho is our process however the question should apply to all as matching -maintaining & repeating color on more than one shift can challenge us!)

 


ANSWERS:
We have a spectrophotometer and we scan the press okayed sheet and record that data and when we rerun the job we run to the old numbers. This works great for us.


Easy answer – the last sheet the client signed off on and with a signature and date. That tends to eliminate all the other mentioned variables.


We save our information on the computer at press. This would include sequence, ink densities and water speeds. For the most part we pull up very close to the previous printed sheet. We do not save plates from run to run but they (prep department) are confident that nothing changes, yeah right! You are correct to believe there are many changes in the press room especially if the maintenance is not kept up. Blankets, rollers, ink and fountain solutions are all subject to problems if they are not consistent throughout the pressroom.

I think your first step is to make sure the curves are set properly to match each other. To test that part might be to have the plates made at one location then have them tested at both locations. Just a thought.


With the implementation of closed loop color we simply document the plate curve used, the press the job was run on, and the densities run on both the Electronic Control form and Electronic Timecard we use which are both available to the Operator that runs the reprint.

We will have a previously printed sample available on the reprint as we keep one copy of every printing as a reference. We also will have the density numbers available on the Electronic Timecard we have in house. Any special customer requests are kept in a notes section on the Electronic Control Form.


If it is a repeat job, we keep and match the last press sheet.


Very seldom do we do press oks. We charge $125 minimum plus press time. We had one project where new customer showed up 2 1/2 hours late we pulled job off press and re-scheduled for the next day. They paid for the time and the job. Exact reruns we would use the last played proof if available. Customer would resign it to protect us both.


We handle color 2 ways. I believe I detailed it out once before in response to a question, so without getting to carried away in detail here it is.

We can identify unique areas to hit color, but there is a trade off, and gain in one area will be a loss in another. The amount of change is extremely variable across software and if it is being done at the production or prepress/design level. We obviously handle the adjustments at the production level. When we produce {our product} we are very careful with colors as they reproduce on a variety of stocks.

Things are different when we are concerned with the overall look of the print as a whole. With both sheet fed and wide format we want a high quality print that grabs the eye and carries it through the print. Like a child in a candy story, even if for a second, we want print that evokes senses and emotions for the viewer. When we get feedback that sounds like, the print is bright, even, smooth, deep, vintage or patina we know we are doing well. This is all based on the idea of “Appealing Color”, and most of my customers who bring nicely created professional art are asking for this.


We continuously run to the original approved color.


We have encountered similar issues to those noted {in the question}. My experience has shown that if variables such as changes in substrate type, and ink/chemistry on press are eliminated from the equation, the most noticeable change is then age of the previous printed sheets. I have seen noticeable change in less than 24hrs. Process inks, “Dry Back” and lose their intensity. We insist from our ink supplier that they verify consistent Spectrophotometer readings of our Process & PMS inks to ensure they remain consistent from batch to batch.

We have found that the best way to keep color consistent over time is to run to the same ink densities that we used on the first run. This assumes that there have been no significant changes to the workflow, from Pre-Press, to substrate, to ink, varnish/coating/ chemistry, etc. Off line treatments also will affect the color of the piece, such as UV Coating, Laminating(especially “Soft Touch), Foil stamping (from the heat). We save “OK Sheets” both prior to, and after any off line effects.

We have recently been G7 certified, but prior to that, we performed our own color calibrations, running test forms on a quarterly basis, and comparing them to previously set standards, and verifying our proofing solution was accurate and consistent with what our presses can reproduce.

We save one “Press OK” sheet for each side of each form we print, along with retain sheets pulled throughout each press run. We affix an “OK” sticker to the approved sheet, signed by our client in the event they press check the job, or by our senior press operators. On this sticker we record press info pertinent to each run; date, ink sequence, density, filter, coating/varnish type, etc.

We will save an “OK Sheet” each time we repeat a job, and reference back to them, as well as the original color proof. Our history has shown that, eliminating/minimizing as many variables as possible, keeping our presses maintained and in a known or repeatable condition, (roller settings, blankets packed correctly, etc.) and “running to the numbers” has given us the most repeatable results matching color.


We document our press densities on a label of our approved press sheet and use spectrophotometry on our press console to load all the settings on to backup disk. We keep original sheet, prepress proof, and last color run(s) and just keep filing under the latest job number.


We record the wet densities, any “ink charges” if used, and ink sequence.
We will use original color okay but being aware how the paper may fade in color and affect the ink color. We will reference the last run color okay as well.


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