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Starch Pastes, etc.

Hi, Gudrun,
If you can easily lift a pastedown a day or two after putting it down I
would guess that you pasted down closed with a moisture barrier between the
pastedown and text block and that the adhesive bond was not completely dry.

It has been my experience, whether lifting an old pastedown, removing an
old cloth or paper lining, or removing old hinges from art-on-paper that
the paste is neither easily nor completely reversible.  There are two kinds
of failure in this situation: bond failure or adhesive failure.  If the
bond fails while lifting a pastedown, either the board or the paper will be
skinned.  If the adhesive fails, there will be remnants of adhesive on both
the paper and the board.

In the European tradition, things stuck together should stay stuck together
and bond failure is expected.  In the Asian tradition, there are times when
adhesive failure is desired and very thin pastes are used, to facilitate
separating things while dry.  When I restore Asian folding screens I often
use a starch paste so thin the paste dish looks like it's full of gray

Sometimes, when removing covers from saturated, water damaged bindings the
pastedowns will slip off of the boards fairly easily, but even when the
whole text block is soaking wet, it is not uncommon for a thin laminate of
the board to come off with the pastedown, if there was a good bond.

People have different preferences regarding how wet or dry a paste they use
and vary that according to the porosity of the paper going down, the board
it is being adhered to (paste board, binder's board, or rope board),
whether they want the board to lie flat or have a slight inward curl,
whether they paste down open or closed, and how much open time they like
after pasting before putting the two parts together.  Each of these
criteria will affect the ease of separation, but there will still be more
or less paste on one or both of the surfaces.

The easiest time I ever had lifting a pastedown was on a 17th century book
where the binder used a flour paste so crude that there was still bran in
the adhesive; most of the paste stayed with the pastedown as it was lifted,
suggesting, to me, that the paste was fairly dry by the time paper and
board came together.

Hope this hasn't seemed too much like the zen of pasting.
Take care,

>Date:    Tue, 1 Apr 1997 21:48:24 -0800
>From:    Gudrun Aurand <aurandg@xxxxxxxxxxxxxx>
>Subject: Re: Starch Pastes, etc.
>Jack C. Thompson wrote:
>> A properly made and applied wheat starch paste is not very reversible,
>> contrary to what some people have said....

>> hello jack,
>i pose this question on the list, since more people may be interested in this
>would you explain what context you are thinking of when you say wheat starch
>paste "is not very reversible"?
>my experience relates only to lifting endsheets a day or two after pastedown,
>when i didnt quite like their fit. i remoistened the paste-down and was able
>to lift it without difficulty.
>i do blelieve i busted those membranes properly when preparing the paste.
>greetings gudrun

Jack C. Thompson

Thompson Conservation Lab.
7549 N. Fenwick                               I hear and I forget,
Portland, Oregon  97217                       I see and I remember,
                                              I do and I understand.

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