Last
month, we warned our readers about the perils of unsolicited paper
substitution.
We also discussed the importance of paper
PPI (pages per inch) ratings.
Based upon
readers’ responses, this topic needs further
amplification.
PPI, which is based on the caliper of the
paper stock selected, doesn’t mean much when you’re producing a
16-page saddle bound catalog.
It makes a great difference
when printing 1,000-page books such as we do regularly at
Copresco.
Depending on the paper used, actual book
thickness could vary as much as 1/4” or more. And that affects the width
of the spine for binding.
Paper weight isn’t the determining factor in book thickness. Caliper—the thickness of paper measured in thousandths of an inch (points or mils)—is.
Thickness
is measured in Pages Per Inch (PPI).
PPI is calculated by
this formula:
2
÷ caliper
If math isn’t your strong suit,
check out one of the links in our internet box.
Cougar
Opaque is a well-known premium grade book paper. The caliper for a 60# smooth
sheet is 4.6, while vellum is a thicker 5.2. That’s an 11.5%
increase.
You can see what two minor variations for the
same paper type can mean in the final book thickness.
Here
are other paper properties that directly affect the printing of your
publications, books and manuals.
Opacity is
the amount of showthrough in paper. Opacity is very important in book printing
because it affects how much the back side of a page shows through to the front,
and how one page shows through to another.
The cheapest
and least effective way to reduce showthrough is to increase paper thickness,
usually by increasing the weight.
If a 50#
paper is too translucent, moving to a 60# will ever so slightly reduce the
showthrough. However, it will also increase the weight and thickness of the
book; usually not desirable characteristics.
A better way
to increase opacity is to use an opaque book paper.
Brightness is the ability of paper to reflect light. Bleaching the paper pulp is a way to achieve brighter paper.
Clever
marketing has equated higher brightness with better quality, but this isn't
necessarily so.
Long books
fare better on a more natural off-white shade of paper because they offer less
glare and are easier on the eyes.
Technical manuals work
well on high-brightness paper that provides a better contrast for
illustrations, photos and footnotes.
Whiteness refers to how neutral the color of the paper is. The trend toward greater brightness has led to the addition of more fluorescent dyes to paper, which is cheaper than the bleaching process.
Many “white” papers used to have a decidedly yellow cast. Playing with the shade may fool the eye regarding brightness, but it can also play havoc with accurate color printing.
If you are
presently using premium papers for your books and manuals, let us offer
recommendations for cost saving without compromising quality.
If you’re still using lower-grade commodity papers,
now may be the time to reconsider upgrading your look.
You
may be surprised at how little the extra quality costs.
If you’re still confused about paper or any aspect of digital printing, tell us what you want to accomplish, and we’ll work out the details for you. Just give us a call.
To calculate PPI, simply
enter the thickness of the paper:
http://www.internationalpaper.com/us/en/Business/CPIP/PPI.html
http://www.casepaper.com/resources/calculators/pages-per-inch
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