Poorly maintained Kodachromes mold and scratch as easily as E-6
films. How well are you taking care of your chromes? And I'll wager
that well maintained E-6 films will last just as long as Kodachromes.
My E-6 slides approaching 15 years old certainly haven't suffered any
more color loss than have my Kodachromes–which is to say none that
can be noticed. Maybe in 35 years they'll have become faded enough to
be unusable, but I somehow doubt it.
Proper storage is a given, but there is one key difference between
Kodachrome and E-6 films. Kodachrome is a silver based emulsion,
while E-6 films are dye based. Silver based emulsions are inherently
more stable, hence the archival qualities of Kodachrome. Kodachrome
actually starts as B&W and the dyes are added during processing, so
it actually has storage properties closer to those of B&W film.
On a historical note, the diffusion method of processing used in
processing Kodachrome came about because of difficulties in
developing the dye couplers necessary to include the dye layers in
the emulsion. One effect of this was increased sharpness due to the
thinner emulsion. When Kodak finally got the dye technology right,
they introduced the E-6 films, but Kodachrome was always a better
film. It's technically very difficult to process, which is one of the
factors that led to it's demise. K-14 lines are very expensive to set
up and maintain. Kodak actually closed it's Kodachrome line in
Chicago in the mid 80's because they couldn't get enough quality help
to keep up their standards, and moved all the K-14 processing from
the Chicago lab to their lab in Findley, OH. And I still got 24 hour
turnaround.
