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Re: [BKARTS] Chiming in, Reflections on double fan binding

Thanks Peter for the information on double-fan binding. I am looking forward
to the complete article on your website. Your article gave me something to
think about, but your conclusions were a bit too watery. I think some people
will be confused. Here is what I personally concluded from your article:

   1. Notching is not really recommended when double-fan binding "non
coated" paper.
   2. Notching is generally recommended when double-fan binding "coated"

   1. Notching doesn't increase the gluing area substantially.
   2. Notching stiffens the spine substantially.
   3. Notching increases the strength of a binding by stiffening it and not
allowing the book to open as much, thereby reducing the stress on the
adhesive and paper in the spine zone.
   4. The strings or adhesive in the notches will be subject to tremendous
leveraged forces if someone will apply a bit of pressure to open the book
wide such as in photocopying.
   5. Strings or adhesives often rip out of the paper notches if the book is
forced open.
   6. The strength of a properly made double-fan binding using non coated
paper is quite high already.

   1. Notching is not ideal when double-fan binding non coated paper. The
reduced book flexibility and problems with tearing in the notches is not
generally worth higher page pull strengths achieved.
   2. Notching is a compromised solution for binding coated papers. The
adhesive to coated paper bond when using cold emulsion adhesives is so poor
that something has to be done to increase the binding strength, even if it
results in reduced book flexibility and problems with tearing in the

   1. I tried to bind coated paper after reading Peter's message. The first
big problem I found was that typical coated paper was only 0.002 inches
thick, compared to 0.004 for the non coated paper. When double-fanning, the
steps between pages drops from 0.006 down to 0.003 inches on a 90 degree
fan. This is hardly enough of a step to deposit adhesive on. So I used a 180
degree fan which I imagine is never done in practice.
   2. Even so my book block did not hold together very well. In my case the
cured adhesive just pulled off the ends of the pages without tearing off any
paper fibers or coating. I cut up an old Canada Computes glossy magazine and
the coating they use pretty much seems to repel the glue. The magazine is
stapled together.
   3. I did a clear packing tape test to see if the surface of coated paper
was much weaker than non coated. The packing tape appeared to pull of the
surface of both papers about equally well.
   4. I glued non coated paper to itself and coated paper to itself and both
stuck very firm. When I tried to rip the pieces apart the top half of the
surfaces of both tore away. Seems like gluing the larger area worked better
than when double-fan gluing.
   5. The cold emulsion adhesive seemed to cause a major buckling of the
coated paper.

   1. 90 degree double-fanning normal non-coated 0.004 inches thick paper
exposes only 0.006 inches on the edge of the paper which is very little.
When flipping the book block the glue will however will be dragged
underneath the mating page double this distance. Ideally this would move the
glue line to 0.012 inches from the page end. I wonder however how much glue
would travel this far down. I would think that most of it is scrapped off.
   2. It is hard to get more of the page sides exposed as we are limited in
how much we can arc the book block.

   1. The cold emulsion adhesive has long molecules. Other tests I have done
seem to indicate that it is very difficult to push the adhesive molecule
down below the surface of the paper. Even by squeezing the adhesive with
strong mechanical pressure I could hardly get the adhesive down 0.002
inches. I could tell because that is were the paper delaminated.
   2. The adhesive is an emulsion. Even seconds after the adhesive is
applied the paper sucks water from the adhesive which makes the remaining
adhesive molecules link together further preventing the adhesive penetrating
the paper.
   3. Ideally the paper should absorb the adhesive and release it when the
book block is slide, but not enough adhesive is absorbed, only water.
   4. Paper is not very strong in delaminating.
   5. Cold emulsion adhesive shrinks on drying which reduces the area
   6. Coatings on paper compound the problems above.

MY OWN  FLEXING ANALYSIS (after thinking about Peter's)
   1. The pages of an adhesive binding should never lay completely flat (180
degrees dead flat). Imagine that there is a tiny layer of adhesive between
each page, maybe 1/10 as thick as the page thickness. It would be impossible
to stretch this thin layer to 180 degrees.
   2. To open 180 degrees dead flat, the paper itself therefore must stretch
in thickness as the binding is opened. It is not likely that paper can
stretch in thickness much, but that's probably what happens as Peter pointed
out. There is probably some failure of the fiber bonds to allow some
thickness movement. There are still some remaining fiber bonds and so the
paper doesn't lose much strength.
   3. It is probably much more ideal that the paper also bends in a gentle
arc beyond the bonded section.
   4. Most of my bindings have used a 0.010 thick muslin cloth. This seems
to slightly reduce the flexibility and reduces the angle of opening between
   5. Too thick a backing cloth would result in leverage forces that would
pop the glue between the pages. I don't know if 0.010 is too thick or not.
   6. Glue filled grooves are used when trying to limit the flexibility
beyond just using a backing cloth because now the limiting material is on
the inside of the glued together pages. This doesn't pop the glue between
the pages if balanced with a backing cloth on the outside of the glue layer.
   7. The glue layer between pages is not really that strong between
sections of an opened book. A strong backing cloth prevents the opened book
from splitting between each opened half when handling the book. I use 0.010
thick muslin cloth which is stronger than open weave mull and appears to
stick just as well.
   8. Open weave mull is too flexible in the flat plane and so the spine can
bend too easily in the longitudinal direction.
   9. Non-woven materials such as paper and Tyvek are not ideal for the
spine lining. They are too stiff in the flat plane and on thin books shear
off the book block when the book block is flexed in the longitudinal

   1.  Cold emulsion adhesive seems to be lousy in terms of penetrating
paper. It would be good if the adhesive could soak completely into the paper
and form a continuous layer of fiber reinforced polymer at the spine.
   2. An even stronger adhesive than cold emulsion would be nice.
   3. All paper is essentially coated and filled. Even common non coated
office paper have up to 50% fine particle fillers and coatings. "Coated"
papers seem to have a solid barrier coating. These coatings seem to prevents
the cold emulsion adhesive from penetrating.

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 "Urban Travel Issues"

-----Original Message-----
So what does this have to do with notch bindings and rigidity?  As you
stiffen the spine you inhibit the full opening of the book.  This prevents
the attachment between the pages from reaching a breaking point.
With this knowledge in hand I learned that I could increase the page
pull strength of coated papers significantly by controlling the spine (I
have numbers but it is Saturday night and this isn't supposed to be a
research paper) .  The amount of control needed depended on the
drape (the flexibility) of the paper.  Conversely,  I found that I gained
little or nothing by stiffening the spine of books with uncoated paper.
Page pull tests (like Ben, I built my own tester) remained comparable
for a flat-opening, uncoated-paper book and a uncoated-paper book
with a more controlled opening.

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