RE: Coating and/or conservating

AFAIK, Kodak's recommendations regarding coatings are based on research done
on gelatin silver and chromogenic papers. While they generally supported the
use of lacquers in a 1972 publication "Retouching Ektacolor Prints", their
1982 publication "How Post-Processing Treatment Can Affect Image Stability
of Prints on Kodak Ektacolor Paper" warned against the use of lacquers,
citing several dye instability problems caused by various solvents. The same
recommendations appeared in several Kodak publications in the 1980s.

Kodak Print Lacquer was a cellulose acetate butyrate lacquer introduced
c.1940 and discontinued in the 1970s. I don't know why they discontinued it,
though it was a relatively small market, and by the 1970s McDonald and
Lacquer-Mat were both well established and were selling fairly similar
products.

Kodak's research however may not be relevant to the issues of coatings
applied to alternative processes, particularly coatings like waterborne
polyurethanes, which would likely be impossible to remove. Apart from the
questionable long term stability of any particular coating, you can also get
changes such as delamination at the coating/print interface. Protection from
oxidation is certainly a quality that can be attributed to many lacquers
applied to gelatin silver prints, though if such protection is the primary
goal, toning may be a more effective long-term strategy.

While artificial aging and stability studies certainly have their place,
they cannot predict with any certainty the long-term stability of a coating
in contact with a photographic print. If you are going to apply synthetic
coatings for aesthetic effect, be aware that you may be compromising their
long-term stability. Though there certainly are compelling reasons for the
use of coatings-- protection of the print surface when displayed unframed
and the increased saturation/Dmax being the two most common that I can think
of. Artists must work how they see fit though, and sometimes there are most
pressing concerns than long-term stability.

For those interested in coatings on photographs, there is a book on the
subject being published by the Photographic Materials Group of the American
Institute for Conservation. It will be out in a couple of months, and I'll
post an announcement when it is available.

Gawain Weaver

 
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Richard Knoppow wrote:

   At one time Kodak recommended coating prints with their
print laquer for protection. This recommendation was
ammended later because it makes it difficult or impossible
to treat prints which have had problems. I think Kodak also
made a film laquer.
   At least in theory, the laquer should help protect the
image from oxidation. The samples you give tend to support
this. I think the issue is more complicated so I am not sure
coating should be done routinely.
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Received on Wed Feb 8 13:29:23 2006