[Table of Contents] [Search]


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Vellum



In 1971 I visited Sandy Cockerell and Roger Powell in England. Both were
working with vellum at the time. Cockerell was doing those beautiful gold
and black tooled vellum (over board) bindings with the parallel lines and
gold discs. He adjusted the climate in his studio to match the temperature
and humidity of the libraries to which the books were going, in an attempt
to minimize the effect of hygroscopic warping. But he told me that within a
month one he had shipped to Canada had warped anyway.

Vellum is very particular, and compensating with paper on the opposite side
doesn't always work, for several reasons:
1. The coefficient of expansion with changes in moisture content is
different
2. Vellum is usually stronger than paper, and exerts a greater force when
it changes
3. The humidity outside the book changes faster than it penetrates the
pastedown
4. Vellum isn't uniform in its hygroscopicity, even if split to a uniform
thickness. The composition of the skin varies (e.g., hornier over bone,
stretchier in the stomach and armpits), and different skins from the same
species will behave differently depending on the age and diet of the
animal.

So even small changes in temperature or humidity can warp a binding. Why
temperature? Because relative humidity (rh) is a temperature-dependent
variable, and different materials can absorb moisture at different rates at
different temperatures. So even if you balance the boards so they're flat
at a particular temp/rh point, and even if you compensate for the vellum on
the cover with a vellum pastedown (was it Rogers of Halifax who did that?),
it still may warp at the same rh if the temperature is different.

Limp vellum bindings often have no pastedown, and are often entirely
non-adhesive. That solves a lot of these problems, as the vellum can change
size with impunity.

Roger Powell was doing something different. He was in the process of
restoring a Hebrew manuscript on vellum, where he had washed the pages and
was drying them on a frame with bulldog clips all around the edges of the
leaves held by rubber bands attached to pegs on the frame. This kept
tension on the pages from all directions as the vellum dried and
contracted. There's a photo of this in my book, _Minsky in London_.

About 8 years ago Sotheby's asked me to restore Andy Warhol's Bugatti
rocking chair. It was stretched vellum over a wood frame, with painted
designs, and the vellum had split in the middle of the back, probably from
being in a heated warehouse in the winter. I built a tent in my studion
with plastic dropcloths and put a humidifier in it with the chair. It took
a month for the vellum to relax completely. Working from the back of the
vellum I patched it with a piece of natural sausage skin, using an adhesive
made (similar to Jack Thompson's) of flour paste, pva (Elvace 1874), and
boiled down vellum. I developed it by trial and error, trying many
different combinations of adhesive, gluing sausage skin, vellum and
parchment to two pieces of vellum (hydrated), and drying them. This one had
the right combination of tack and slip for workability, stayed flexible
after drying, and is invisible. It had to be invisible, because the chair
frame had vellum on both sides and light passed through it. Unlike the hide
glue method, it is applied at room temperature, which was important to me
because it gave me more working time. After completing the repair I slowly
reduced the humidity in the tent (one month), and the chair looked (and
worked) like new. Of course, I cautioned Sotheby's to keep it in a climate
controlled environment, and to advise any purchaser to do likewise.

I first learned about the power of vellum when I was working with (ane
learning from) Daniel Gibson Knowlton, who was then the bookbinder of Brown
University. In 1969 he gave me a 16th c. Martin Luther to repair, that was
vellum over wood board. The vellum contracting had split the wood in half.
I had to remove the vellum from the wood, repair the board (pegs and glue),
reattach the vellum (straight flour paste), patch in a few pieces of vellum
where the original was missing, and blind tool the patches to match the
tooling on the original.

The only paper I've found which is similar in it's "pull" to vellum is
called "Elephant Hide," and though I haven't bought any in a few years, I
used to get it at NY Central Supply on 3rd ave. and 10th St.

--

Richard
http://www.minsky.com


[Subject index] [Index for current month] [Table of Contents] [Search]