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Re: Fountain of Youth



Thanks again, David, for the illumination about the process. One would
hope that every binder who uses leather would read through the "skin
deep" series.

As you suggest,  the articles at http://www.hewit.com/sd4-leat.htm and
http://www.hewit.com/sd7-leat.htm
are very much to this point.

>I would have thought that these leathers would have
>been extremely difficult to use both in the preparation
>(Paring) and in the binding, due to their extreme hardness
>and brittleness.

They are not as soft as fatliquored skins like Chieftain or Clansman,
but they are by no means horny or brittle. Perhaps going through the
shaving machine, with the helical blades, softened the skins
mechanically through stretching. I also boarded them, not exactly by the
method illustrated in "Skin Deep", but by rolling the skin over itself
with a board, grain to grain.

Also, when I apply the leather to a book it is thoroughly wet-- First I
wet the grain side with water, then I paste the flesh side with flour
paste two times, allowing it to almost surface dry before the second
application. The skin in this state is very pliable.

In blind tooling I also wet the skin. First I tool blind on dry skin
through my pattern, then directly on the skin. Then I wet the skin
slightly and tool again with a cold tool, then with a warm tool. That
gives my lightest impression. For darker impressions I wet more and use
a hotter tool.  When the skin dries it is harder that a fatliquored
skin, which seems to make the tooling impression crisper. If I am going
to gild the tooling I then do so in the dry skin, and it gives a very
clean impression. After tooling I oil it fairly heavily, and allow the
oil to soak in overnight. The next day I wipe off any excess oil and
polish it with a soft cloth.  Since the leather has been recently wet
through, it has a fairly high moisture content, so the issue of overdry
oiling doesn't arise.

Some conservators disparage the oiling of books. David suggests that
treating the leather surface should depend on the type of tanning
process and the storage conditions of the book. I expect that in 50 or
100 years there will be a lot of work for binders, repairing un-oiled
books that have split at the hinge. The mechanical properties of leather
are most important at that point.

There are all sorts of opinions by experts in conservation and
preservation, but does anyone discuss the issue of the mechanical wear
from friction within the leather if it is unlubricated? Unlike vegetable
materials, leather has a cell membrane and no cell wall. That membrane
is all that holds in the cytoplasm. Perhaps my understanding of the
structure of leather is in error, but it seems to me that when
functioning as a hinge the cells have to slide over each other. If there
is friction the cell membrane will wear through, leaving loose tanned
cytoplasm with no structure, or leather dust. It also seems that
migrating sulphuric and sulphurous acid from pollution (hydrogen
sulphide and sulphur dioxide combining with water vapor?) can destoy the
membrane having a similar effect. Wouldn't treating the leather with
something like Marney's (lanolin + neatsfoot + beeswax), particularly in
polluted environments, reduce both the mechanical and chemical hazards
by lubricating the skin and sealing the surface?

Are there any websites illustrated with microphotography of leather that
address this issue? Again I would like to turn to David or to Jack
Thompson for some clarity on this.
--

 Richard
 http://www.minsky.com
 http://www.centerforbookarts.org

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