13th century vellum manuscript

Katrina Ben <kben [at] slv__vic__gov__au> writes

>The manuscript is in an early 20th century binding with copious
>animal glue on the spine.  The sewing supports are beginning to
>break down and the manuscript opens with great difficultly. This
>type of vellum is extremely moisture sensitive, and my concern is
>whether the glue can be removed without causing any damage to the
>vellum. ...

I encountered this problem with a 14th century Book of Hours which
had been rebound in the late 19th century using furniture grade hide
glue on the spine, which had destroyed much of the edges edges of
the outer bifolia.

Brushing on a 3% solution of methyl cellulose I softened and removed
the glue.

The textblock was held in a lying press and only two or three
gatherings at a time were treated.  The methyl cellulose was covered
with a strip of thin Mylar while it softened the glue (if the glue
is allowed to dry before it is removed it takes longer to
re-activate it).

When the glue had been removed it was necessary to replace the
missing material on the outer folds of the bifolia.

Using vellum was not an option, since that would have greatly
increased the width of the spine, so I made guards of goldbeater's
skin which I made from ox intestine, adhering them with gelatin.

The textblock was then resewn into a concertina of Japanese handmade
paper and bound into quarter split Oregon white oak boards which I
had begun processing some years before, in anticipation, with brass
fore edge clasps.

Jack
Thompson Conservation Laboratory
7549 N. Fenwick
Portland, Oregon 97217
USA


                                  ***
                  Conservation DistList Instance 26:21
                Distributed: Saturday, October 13, 2012
                       Message Id: cdl-26-21-003
                                  ***