How widely it was used prior to that time, and what filmstock selection practices specific institutions followed I don't know, though I suspect these may have varied.
As for current polyester filmstock:
Black-and-white polyester film has a life expectancy of 500+ years under proper storage conditions.
<https://www.nedcc.org/free-resources/preservation-leaflets/6...>
How widely it was used prior to that time, and what filmstock selection practices specific institutions followed I don't know, though I suspect these may have varied.
As for current polyester filmstock:
Black-and-white polyester film has a life expectancy of 500+ years under proper storage conditions.
(From the same source.)