Polaroid prints

I thought about creating a full answer to the Polaroid question that was
on the recent DistList.  Unfortunately, the technology is so complex
that it would be another multi- multi - multi - page thing.

However, the short answer to the question is "yes."

All of the color Polaroid technology is based on a process known as
alkaline induced dye diffusion transfer.  The photograph contains
silver-halide, dyes and developer.  The pod ("Open the pod bay doors
Hal") contains mainly a strong alkaline in gel (usually sodium or
potassium hydroxide).  In the case of integral prints (SX-70 and
Time-Zero) it also contains opacifying dyes.

The dyes, in the presence of the alkaline gel, migrate to the receiver
sheet.

Usually behind the receiver sheet is the timing layer consisting of a
barrier and an acid.  The alkaline slowly diffuses through the timing
layer barrier to meet the acid.  The acid and alkaline combine to form
water and a salt. The water breaks down the barrier layer and the acid
(now in solution) is spread across the surface of the receiver sheet.

That's the basics.  The technology varies from chromogenic alkaline dye
diffusion transfer to "silver assisted dye release/alkaline dye
diffusion transfer" (used in SX-70, Spectra, 600, 600 plus and Time-Zero
films.)

There are also all kinds of other stabilizers and "stuff" in the film.
So the two problems are "what's still in the Polaroid that will get out"
and "what's still in the Polaroid that will react with things that get
in?"

As a general rule, Polaroids should not be stored with other things
including other photographic processes, newspaper clippings, papers,
faxes, etc.  As an example of the sensitivity, some people used to clean
their SX-70 prints with Windex.  (You used to hear Henry Wilhelm talking
a lot about this.)  The Windex contained ammonia (thus an alkaline
solution) which caused the dyes in the prints to "migrate" severely.

BTW, SX-70 is not exactly a "new" process.  It was first introduced in
1972. The newer versions of the integral prints (non-peel apart) are
Time Zero (1979), 600 (1981), Spectra (1986) and 600 Plus (1988).

Doug Nishimura
Image Permanence Institute

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                  Conservation DistList Instance 7:29
                 Distributed: Saturday, October 2, 1993
                        Message Id: cdl-7-29-001
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