Does Kodachrome 40 Ripen over Time...???

[Alex]

I was never able to do any kind of study to substanitate the idea that perhaps Kodachrome 40 "ripens" over time.

By Ripen I mean that if you buy Kodachrome 40 that is a year or two from the expiration date, it will have more of a greener, yellower tone, but if you shoot Kodachrome 40 as it nears it's expiration date, (or even beyond by up to 6 months to 1 year), that it will have "warmer" tones with more reds and warmer oranges.

Any opinions on this idea?

[Actor]

It's true.

Professional films do not have an expiration date. The assumption is that the film will be used immediately so an expiration date is not needed.

Consumer films have "process before" dates. The assumption is that the film will not be used immediately but will have significant shelf life either in the store or the consumer's closet. The dye's do age and different colors age at different rates. The film is manufacturered so that the dyes will reach a proper balance at some future date.

Whether the film warms or cools with age I do not know. However, if processed before the expiration date the differences are pretty much negligable.

I have some new K-40 with a date of 3/2004. Based on that my guess is that Kodak dates the film 18 months after manufacture.