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Re: [BKARTS] Double-fan binding - Spine exposed by notching



Great information Gregor:

Would you mind however clarifying your statement that "many shallow notches
effectively increase the
(length) of the spine that is exposed to adhesive by X3." Isn't that
statement a bit misleading?

When double-fan gluing, isn't it the total glue area that is important? A
simple sample calculation shows the following:

   1. Non notched spine side area of page exposed to adhesive = 0.004 x 11
inches = 0.044 sq inches
   2. Notched spine side area of page exposed to adhesive = 0.044 x 3 =
0.132 sq inches
   3. Paper sides exposed to adhesive = 0.010 adhesive penetration x 2 sides
x 11 inches = 0.22 sq inches

   4. Total area non notched per page = 0.264 sq inches
   5. Total area notched per page = 0.352 sq inches

So it seems that notching only increases the total glue area slightly, it
has 1.33 x the area and not 3 x the area as is often thought. One could
increase the glue penetration only slightly on the side of each page and
achieve the same total glue area. This would result in greater spine
flexibility? Maybe notching is desirable in practice because it roughens up
the paper fibers, but wouldn't just exposing the fibers be better?

Ben Wiens...applied energy scientist
Ben Wiens Energy Science Inc.
8-1200 Brunette Ave. Coquitlam BC V3K1G3 Canada
E-mail: ben@benwiens.com
Energy Website: http://www.benwiens.com
Read my popular web-booklet "The Future of Fuel Cells"

-----Original Message-----
Hi Ben and others:

With regard to notching vs no notching when doing double-fan adhesive
binding I must add that notching is not always necessary, and when it
is done, it is not always done properly. As you have mentioned a deep
notch (by this I mean 1/8 inch or more) may actually defeat the
purpose of double-fanning by not allowing for an easy opening book. A
deep notch allows adhesive to form cleats that resist the lay flat
characteristics of the double-fan bound book. If you force open a
book that has been deeply notched (pretend you are smashing it down
on a flat plate photo copier) those little cleats may actually tear
the paper.

Very shallow notches of about 1/16 inch ( 2 mm) or less work very
well. Especially when they are cut by a milling knife that clean,
sharp and has many teeth. Our notching knives are cut in a
trapezoidal shape. The many shallow notches effectively increase the
(length) of the spine that is exposed to adhesive by X3 !!

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