Generic question about film negatives

[UniSol GR77]

How many decades are the original film negatives or interpositive masters supposed to last? 50 years or even more?
Of course, we're talking about film negatives and interpositive masters properly stored by a company.

Thanks...

[42041]

Modern color negatives can supposedly last centuries in a properly climate controlled environment before significant fading occurs. Much of this improvement was done in the 80s, film stocks of the 70s and 60s were much less durable and will be lucky to last the better part of a century before fading is problematic. Color negative of the 50s (and very early 60s) is even less robust (most of those films already have serious fading/yellow layer failure), and also the early acetate "safety" bases used in the 50s had durability problems (so-called vinegar syndrome), though I believe that was ironed out within the decade.

That's the general idea anyway, there other factors at work, like quality of processing, the density of the negative, any wacky chemical processing, etc.

Black and white film (including 3-strip technicolor) is chemically stable and should last indefinitely, though the nitrate base used before the 50s is very flammable, and they started using those vinegary safety bases in the 50s.

[Robert Harris]

Originally Posted by UniSol GR77

How many decades are the original film negatives or interpositive masters supposed to last? 50 years or even more?
Of course, we're talking about film negatives and interpositive masters properly stored by a company.

Thanks...

Film negatives over 100 years old still survive.

The worst examples are color negatives, 1955-60. Nitrate is our friend.

RAH