A client of mine recently reprinted a small booklet. It actually wasn’t due to any errors. The book was just very popular, and she had run out of copies. My client had initially printed 300 each of two versions (one in Spanish and one in English) at a custom printing vendor with both offset and digital equipment.
The initial book printing run of both versions had been digital, due to the page count (52 pages) and the short press run (300 copies). A local book printer had produced the job on an HP Indigo digital press. The photos had been brilliant and alive, and the heavy coverage solids were vibrant and consistent.
That said, the second book printing run involved significantly more copies (1,500 of the Spanish version and 300 of the English version). Since the book printer wanted both versions to be of equal quality, he offered to gang the two jobs and print the entire run at a discount via offset lithography.
The problems my client found
My client found two problems in the final product: too much show-through (the paper was not as opaque in the second press run as in the first), and minuscule white spots on the solid ink coverage within the text. The second problem was minimal, and was due to dust on the printing plates. And, in all fairness, my client brought both flaws to my attention as minor ones. She accepted delivery and used the books. She just wanted me to know she was not completely satisfied.
The research I did to get answers
Since my client had asked why the paper was thinner in the reprinted book than in the first book printing run, I started by measuring the caliper of the paper with my micrometer.
First Press Run
Cover .080”
Text .042”
Second Press Run
Cover .072”
Text .040”
The book printer checked the specifications for the paper, and confirmed that in fact the books had been produced on the same cover and text sheets in both the initial printing and the reprint. I asked if there had ever been any variance in the thickness of different lots of paper he had received from the mill, and the printer noted that this did happen from time to time. However, based on measurements with the micrometer, the paper was still “in spec.”
My next thought was that the apparent difference in opacity—allowing images and text from the back of a page to be slightly visible through the front of the page—might have been due to a paper mill variance in quality. Again, the printer noted that the paper opacity was still within acceptable tolerance.
An “aha” moment based on the research
Several facts about the paper came together for me:
- The paper was 80# Sterling gloss text and cover, thick enough to minimize show-through but still not an opaque sheet (a printing sheet specifically formulated to minimize show-through).
- The text and cover of the booklet included large areas of heavy ink coverage and large photos, design elements that—all other things being equal—would magnify show-through problems.
- The books had been printed using different printing technologies. The first book printing run had been digital, the second offset.
The meaning of the “aha” moment
The fact that the printing paper was not specifically an opaque sheet, combined with the heavy coverage, made sense to me as characteristics that would magnify ink show-through. But I wondered about the inconsistency. Why had there been problems with paper opacity in the second book printing run but not the first?
Digital printing is relatively new, and many printing companies either don’t have both offset and digital capabilities or they are not yet sensitive to the nuanced differences between them.
Both jobs were printed on a coated sheet, so the pigment of the ink (offset technology) and toner (digital technology) should have adhered to the paper surface and not seeped into the fibers (which makes show-through more visible).
However, the thickness of ink on one side of the sheet also increases or decreases the ink show-through from the other side of the sheet. I wonder if the thickness of the offset ink film exceeded the thickness of the digital toner.
The book printer noted that the text pages had been varnished to minimize scuffing. He thought this might have led my client to think that the paper used in the offset book printing run was thinner than the paper from the digital run. This may have been true, but it didn’t account for the problems with opacity. Rather it just accounted for the differences in perceived thickness of the paper.
I don’t have answers here, just questions. But what is certain is that even with the tremendous improvements in digital printing over the last several years (after all, my client did not note any differences in photographic image quality between the digitally printed and offset printed photos), there are still differences between an offset printed product and a digitally printed product.
The outcome of the events
The custom printing vendor was generous. He realized that although the flaws were minor (and not even out of acceptable industry tolerance) and did not detract from the usability of the book, my client was not happy. She needed something. He was generous and gave her a ten percent discount, knowing that she printed multiple titles each year, and that she would be likely to return if she felt she had been understood and treated well. My client was happy. We moved on.
_________________
If any PIE Blog readers have any ideas as to what accounted for the perceived difference in opacity, please leave comments on the blog and let me know your thoughts.
This entry was posted
on Saturday, October 22nd, 2011 at 7:41 pm and is filed under Book Printing, Digital Printing, Paper and finishing, Printing, Soft Cover Book Printing.
You can follow any responses to this entry through the RSS 2.0 feed.
Both comments and pings are currently closed.