Archive for the 'paper' Category

#37: Monitoring Digital Presses

Published
by
Jim Raffel
on August 9, 2006
in blogging, calibration, guidelines, measurement, paper, press run and process capability
. 0 Comments

At ColorMetrix we have some new and potential new customers who will be using our products (both ColorMetrix and ProofPass.com) to monitor and control digital presses like the HP Indigo, Xerox 8000, and NexPress. During our sales presentations most of these folks have expressed concern that the device is constantly self calibrating and correcting itself, so why would I need to do external process control?

My short answer: “Do you really want to let the fox watch the hen house?”

For the most part the internal controls on digital presses are built to keep the device in calibration. While these devices are different than conventional printing presses, they are not so different that we conventional printers do not understand them. There is a certain amount of variation that a conventional press self adjusts for like automatic register controls and the like. So, if we follow this augment to a logical conclusion that would mean process control would be useless on a conventional press as well. If you are reading this article I am fairly certain you do not believe that.

In general the act of process control requires the user to view the device (press in our case) as a black box. By measuring the resulting print the device produces, we are taking into account everything that happens in the device and the environment the device is in.

For example, several of these devices “self-calibrate” by imaging on a drum or a belt between actual substrate impressions. It seems to me we have removed a pretty important piece of the quality puzzle from that equation. What if our substrate is stored in a warehouse with no air conditioning and our press is in a climate controlled room? A week or so ago it was almost 100 degrees with very high humidity in the mid-west. If we bring that paper from the warehouse into the production room and do not provide 24 hours for the paper to acclimate, do you think we would get the same print result as we would with paper that had been acclimated?

If you said NO, please call me for a free trial version of ColorMetrix or ProofPass.com so you can measure it yourself.

In conclusion, all the variables that contribute to a printed piece like; faulty RIPs, toner changes, device wear and tear, paper changes, etc are viewed by a process control system like ColorMetrix as a black box. Process control systems like ColorMetrix measure the finished piece in order to accomplish two goals:

  1. Confirm that the finished print quality is within acceptable quality guidelines
  2. Provide detailed enough information to track back the problem portion of the process when #1 above is not achieved

Overall, the goal of the manufactures self-calibration procedure to stability of the imaging process itself. The goal of a system like ColorMetrix is overall print and color quality of the printed piece you put in the hands of your customer.

#29: Inkjet proofing on the exact paper you print on

Published
by
Jim Raffel
on March 29, 2006
in Print 05, inkjet, paper and proofing
. 0 Comments

During Print ’05 in Chicago ColorMetrix shared a booth with AbsoluteProof, who also invited Pierre Ferland from The Whole Proof. The Whole Proof has developed an innovative new technology which allows virtually any printing paper to be specially coated and then utilized on an inkjet printer for proofing purposes. In last week’s Golden Nugget I discussed the importance of gloss being the same for two printed samples to appear the same. What I found interesting when I requested “bullet points” from Pierre to prepare this week’s e-mail is that he addressed gloss better than I could have while explaining the importance of his product. So, the rest of this week’s e-mail is provided by >Pierre Ferland of The Whole Proof (pierre@twproof.com)

For the cup manufacturer’s story: They were proofing on Epson matte heavyweight paper, but the characteristics of that paper were not consistent with what they were using on the press. The branded inkjet paper was much brighter and smoother than the food grade SBS that they were printing on. When they tried to emulate the SBS’s brightness using the plotter’s ink, it made the paper glossy (typical with pigment-based inks). Even if that hadn’t been the case, very smooth paper reflects light more directly than “fuzzy” paper, which diffuses light. The print buyer and pressman were getting proofs that were much more vibrant than what could actually be accomplished on the “beverage cup” SBS using a flexographic press. Proofing on the same paper they use on the press not only gives their pressman a more realistic target, but it also allows them to set the right expectations with the print buyer, and supply fully functional, full color prototypes made from the actual press stock the whole proof, and nothing but the proof! - Pierre Ferland (TWP International)

Coming next…Jim Raffel’s thoughts on GRACoL 7

#28: The difference between satin-gloss & high-gloss

Published
by
Jim Raffel
on March 21, 2006
in gloss, inkjet, paper and proofing
. 0 Comments

– FREE pass to Monday Night Expo and Paper Show at Print Oasis: ColorMetrix will be exhibiting at Print Oasis (April 2-5Las Vegas) a www.printbuyersonline.com show. The ticket at the link below will get you into the Monday night Expo for FREE.

http://www.colormetrix.com/docs/Paper_Show_Ticket.pdf

*** Golden Nugget #28: The difference between satin-gloss & high-gloss ***

…Everyone has an idea of what the terms “glossy” and “matte” mean. In case of terms like “satin-gloss”, “high-gloss” or “satin-matte”, however, which are often used in the printing industry, different observers may reach different conclusions… (Source: http://www.qipglossmeters.com/glossmeters )

For many years ColorMetrix has quietly developed keyboard wedge software for a line of gloss meters manufactured by Quality Imaging Products. As a result I have had the opportunity to test and work with the Gloss Meters and have also developed a pretty good understanding of why one would want to measure gloss in the printing industry (even though very few of us do).

In the last few weeks I have been assisting clients in understanding why their inkjet proofs do not match press sheets even though they have gone through the entire color management process. The problem in more than one case has been the inkjet paper selection. For sake of argument, we are printing on a semi matte sheet and proofing on a semi-matte inkjet proofing paper. Even if both the inkjet proofing device and the press have been profiled, these two papers are not the same and probably do not have exactly the same gloss. While a paper simulation is nice, it does not adjust for the difference in paper coating which is best quantified by gloss measurement.

Gloss has a great deal to do with how our eye and measuring instruments see images printed on paper. If for some reason you do not believe this, compare an identical advertisement printed in a newspaper versus weekly news magazine.

If anyone would like this quantified, please feel free to send me samples of your proofing paper and the papers you are using this sample to represent. I would be happy to measure the gloss of both and get the results to you.

Coming next…Inkjet proofing on the exact paper you print on.