Double sided adhesive sheets Photographic Activity Test

Peter Verheyen <verheyen [at] philobiblon__com> writes

>Neschen manufactures a product called Gudy-870 which uses an acrylic
>adhesive on a silicon paper carrier. I've seen it listed on 10m
>rolls up to 60cm wide. Gudy 870 has passed the Image Permanence
>Institute's "Photo Activity Test" (PAT), and would be very suitable
>for your uses. I believe the PAT is comparable to the oddy test.
>More information can be found at
><URL:http://www.rit.edu/~661www1/sub_pages/8page8.htm>. In the US,
>suppliers are Gaylord Bros, University Products, Light Impressions.
>Not sure about Europe.

I should clarify a few things about the PAT just to ensure that its
use is not misinterpreted.

The PAT is an ANSI and ISO standard test (not just an IPI test,
although we do run it.) It was developed with input from a number of
labs around the world (including the Australian Archives. Connie
McCabe at the National Gallery, Sarah Wagner, and Steve Puglia
(NARA)) were some of the individuals instrumental in its
development. The proposed test method was balloted by both ANSI IT9
and ISO TC42/WG5 members before it was approved as an American and
International standard test method.

The test uses colloidal silver (roughly in the 10 to 20 nm diameter
range) in gelatin thus simulating a very sensitive silver photograph.
The Oddy test literally uses a piece of silver metal. In some cases,
the silver in both forms may respond in a similar manner, but not
necessarily. The Oddy test may respond to some things that the PAT
detector won't. (Anything that isn't mobile in moist gelatin won't
affect the PAT detector.) However for things that will migrate
through moist gelatin, the colloidal silver should be much more
sensitive due to the very large surface to volume ratio of the
silver. The magnitude of the change in surface to volume ratio as
the particle radius changes is 3/(r-squared).)

Passing the PAT is only one criteria defining a suitable material.
It only looks at chemical interactions that will change an image
(deterioration of a silver image or staining of gelatin.) One might
also want to know about the long-term yellowing of an adhesive or
its solubility over time.

Since IPI can't publish PAT test results, (they're done under
contract), Peter's information is appreciated.

Douglas Nishimura
Research Scientist
Image Permanence Institute


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                  Conservation DistList Instance 16:23
               Distributed: Wednesday, September 25, 2002
                       Message Id: cdl-16-23-002
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