Platinum toning and washing silver prints

I would also like to throw in my two cents worth regarding recent
discussions on the platinum toning and washing of silver prints.

Toning

Back in the 1970s I was asked by Ilford-Lumiere chemists for ideas
concerning the manufacturing and processing techniques of a high quality
fiber base paper. (The paper was eventually named Galerie) We looked at
a number of things including platinum toning, since everyone knows that
the silver--to a degree--is replaced by platinum metal in such a system.

Toned prints were exposed to the usual "gas chamber" torture tests and,
much to our amazement, platinum toned strips turned out to be *less*
resistant to oxidizing gases than untoned samples! Why, you ask?
Apparently for two reasons:

    1.  A significant amount of silver remained in the toned print. This
    silver is vulnerable to attack by pollutants in the atmosphere.

    2.  The toning process, a "classic" formula taken from an old
    photography book, interfered with chemical compounds used in the
    photographic process. These compounds had several functions, one of
    which, (apparently) had to do with the overall stability of the
    image. I was not able to obtain more details, as the exact nature of
    the compounds and their role in the overall system was considered
    proprietary information by the manufacturer.

In the end, the final product, Galerie, was considered a superior paper
for two reasons:

    1.  It pioneered a short processing method which left little
    chemical residue in the finished print. (more on this below)

    2.  It had a thicker gelatin coating (i.e., supercoating) which gave
    more protection to the silver image.

To this I have to add the following: While the above may have been true
for what was at that time an experimental paper, it may no longer be
applicable today, with what one finds in a box of Galerie paper. Indeed,
all manufacturers keep "improving" (a better term might be "changing")
their products on a regular basis.

Washing

I purchased an East Street Gallery Archival Washer after meeting its
designer and manufacturer at a Conservation workshop in Rochester back
in the early 1970s. Anxious to see it in action, but without the
chemicals at hand to test for the presence of residual chemicals after
processing, I thought of using Kodak's Sepia Toner, which is fairly
sensitive to improper fixing and washing techniques. Any significant
amount of chemical residue results in yellow stains overall, or in spots
on the prints. I instructed my assistant to make a number of prints with
wide (3cm) white margins and to wash the prints for different periods of
time, e.g., 20 min., 30 min, etc., up to 24 hours, and then tone each
print with a fresh solution of toner (to avoid contamination).

The results did not make any sense. Apparently, the amount of staining
increased in proportion to the length of time the prints were washed!
Suspecting an error by my assistant, I duplicated the tests myself and
much to my dismay ended up with similar results. Careful examination of
the wide margins revealed that certain areas of the prints (areas that
received a *direct flow* of water from the feeding holes in close
proximity to either side of the print at the bottom of the washer)
showed a darker stain. I then remembered the Kodak instructions to the
effect that water from a tap should never be allowed to hit *directly*
the surface of a print that was to be toned.

I thought that the culprit was the water and therefore had it analyzed
by three labs, all of which reported that my water was "excellent tap
water" with nothing unusual in terms of organic or inorganic contents. I
knew from the scientific literature, that pure water could not be used
to wash prints, as much of the washing process depends on an ion
exchange effect. From the above evidence I concluded that:

    1.  It is definitely possible to overwash papers.

    2.  Papers should not be washed in a system that exposes certain
    areas of the print more than others to a rapid flow of water. (More
    below on why I don't use "archival" washers.)

    3.  Fiber base papers, by their very nature, act like very effective
    filter-papers and are therefore likely to accumulate solids that may
    react unfavorably with a toning process and this may affect the
    conservation of the prints in the long run.

    4.  Much of the problem comes from overfixing in the first place.
    More on this below.

    5.  When comparing toned and untoned sepia prints side by side, it
    is important to also view them by transmitted light on a light table
    to see what is happening *inside* the paper. Toned prints that
    appear to have stain free white areas on the surface, sometimes have
    deep yellow stains inside them.

Around 1975, the Ilford people told us that complete fixing of a print
could be achieved in no more than 30 seconds (instead of the Kodak
recommended 10 minutes) when using an appropriate fixer and continuous
agitation. With much skepticism I tested their procedure using a variety
of papers and at long last, I could easily get sepia toned prints with
bright white margins and highlights!

With this short procedure, which is so well-known that there is no need
to repeat it in detail here, the fixing is kept to a minimum so that the
final wash can be done in a few minutes only using hand agitation and
physically dumping the wash tray a few times. This makes sure that
complete changes of water do take place quickly and that all parts of
the print receive about the same amount of clean water.

Much more could be said on the washing and toning of silver prints and
negatives. Under the best of circumstances even selenium toned silver
images will remain fragile items. When I want a "permanent" print I make
it with one of the carbon processes. Admittedly however, this is not a
feasible solution for every image that one would like to see unchanged
for a very long period of time.

I will have more information on platinum toning in the upcoming (3rd)
edition of History and Practice of Platinum Printing, due in late
August.

Luis Nadeau
Box 7, Site 4, RR4, Fredericton, NB
Canada E3B 4X5

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                  Conservation DistList Instance 7:13
                 Distributed: Wednesday, July 21, 1993
                        Message Id: cdl-7-13-003
                                  ***