From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 05/14/01-09:42:48 AM Z
At 02:15 AM 05/14/2001 -0600, you wrote:
>>>How long do chromes last?
>
>Depends on many factors. I have Kodachrome from the very early days and
>they look as good now as they did the day they were made. My Kodachrome
>sheet films are still good as well. When Eastman made Kodachrome prints
>it was the same process, so they are still good. Incidentally, a
>Kodachrome print was a print made using Kodachrome emulsion coated on a
>translucent base.
>
>However, I have some Kodachrome processed by Technicolor and another
>non-Kodak lab (Drug Store - in the '60s) that have faded and shifted
>color.
>
>One good reason for longevity of Kodachrome is that they are images
>composed completely of dyes - no silver is left in the image.
>
>Agfachromes also have good longevity, judging from some early material.
>Ektachrome and Fugichrome is another story. There are those that say they
>will last a long time and some who say differently. It depends on how
>accurately they were processed, storage conditions, avoidance of
>chemicals and solvents as well as sulfur from rubber bands that all
>contribute to the demise of a slide.
>
>Finally, there is Illfochrome Color Micrographic Film. Absolutely no
>grain, accurate color, extreme sharpness, estimated archival storage of
>500+ years. However, at an ASA of about .005, not very good for most
>applications and about the only stuff you can get is from suppliers who
>stocked the material before Illford discontinued it. Simple P3
>Processing, 35mm as well as sheet.
>
>So the answer to your question is difficult. Film choice, storage
>conditions, care in processing all affect the longevity.
>
>B.
>
The images of all chromogenic color films are composed of dyes. The
difference between Kodachrome and other multi-layer color films is that the
couplers are in the developers rather than in the emulsion. I don't know
what, if any, effect this has on longevity. Kodachrome has good dark
storage life but Ektachrome films have better resistance to fading when
projected. It may be that the exact composition of the dyes are different.
Early Anscocolor, as used for motion pictures, had awful fading
characteristics. Most of the camera originals are useless now, only those
duplicated to B&W separation copies have survived. Early Eastmancolor
negative has fared a bit better but most has faded badly. The same for
still films, not much 1950's Anscocolor or Anscochrome, or
Ektacolor/Ektachrome has survived. Old Kodachrome seems to last forever
with even minimum storage care. I just saw some home movies belonging to a
friend, which are now about fifty years old and look brand new.
Technicolor prints were made with azo dyes so are relatively permanent.
Ciba/Ilfochrome also uses azo dyes.
Its possible that the Kodachrome processed by Technicolor was not
processed correctly and retained some chemical residue causing fading.
Kodak's Rochester processing was always tops.
Kodachrome requires a very complex process which is impractical to do
without automatic machines.
The processing method used for about the first two years of Kodachrome
was a different one than used later. It was truely horrendous requiring
controlled penetration of the bleach and three separate bleaching and
developing steps.
---- Richard Knoppow Los Angeles,Ca. dickburk@ix.netcom.com
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