Adhesive for glass plates

Marsha Sirven <marsha.sirven [at] paris__fr> writes

>We are looking for tape adhesive safe for conservation treatment on
>autochromes and glass plate negatives to seal glass plates together.
>I would like to know if some test has been done on 3M 550 (acrylic
>adhesive on polypropylene support) or on Filmoplast P90 as
>Photographic Activity Test or another test of compatibility with
>silver, pH, chemical composition etc.

The pressure sensitive tapes (our experience in Italy): This system
is not only an archival solution, but a sort of "suture" among the
fragments.

At the beginning Filmoplast P90 was used, a white paper tape with an
adhesive suitable to photographic material, thanks to its neutral
pH.

Yet this tape has the disadvantage to be dull and to make unpleasant
dark areas when printing. Then Permacel was introduced. It was even
used to repair broken cinematographic films, but it turned
unsuitable, too. The matter wasn't the lack of transparency, because
Permacel obviated it, but the acid pH adhesive which could damage
the silver emulsion.

Through the years reversible transparent adhesive tapes, whose
adhesive wouldn't interact with the photographic materials in any
way, have been studied.

The tape we have used in our laboratory is manufactured by 3M, Photo
and Document Tape 001 and turned out not to be interactive with the
silver image and to be suitable (AD strip).

To reassemble the plate, we use micro-pieces of adhesive tape.
However they can't give stability to the broken glass plate
negatives. The tapes let us join the fragments as better as possible
without using adhesive which could interact with the silver image.
They also have the advantage to be easily removable. They must be
obviously placed on the glass side. To avoid the plate breakage when
storing, we will place two acid-free boards both on support and
emulsion sides.

Sara Innocenti
Photograph Conservator
Milan, Italy


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                  Conservation DistList Instance 19:4
                  Distributed: Wednesday, July 6, 2005
                        Message Id: cdl-19-4-002
                                  ***