Film Expiry Date

[Raghu Kuvempunagar]

Anybody knows how exactly the expiry date of film is decided by its manufacturer?

 

[Ian Grant]

The expiry dates for B&W film useed to be 5 years, it's now 2 or 3 depending how long it's in store before confectioning. The shorter date came about to meet ISO 2000 & ISO 9001 certification, it's more about stock and quality control rather than actual expiry date.

Ian

 

[nosmok]

I just shot some b+w film that's been expired for 70 years and got some cool shots, so I take the whole concept with a grain of salt. But I imagine it involves being able to make box speed- I rated my 70yo film at about ASA 1/4 and it was originally 25 or 50 back in the day (sadly, the label didn't make it as long as the film).

 

[cmacd123]

to the maker the date is the "get home free" date. past that date all promises are off.

they no doubt select that date based on their experience with how long they can typically store that sort of film, under the spcified storage conditions, with it still meeting within tolerance all the performance specifications that they promise. that of course includes the time from coating, which may be sometime before the film is converted and packed for sale.

 

[Raghu Kuvempunagar]

Is it possible that two rolls of film that have different dates of expiry could be from the same master roll?

 

[cmacd123]

Is it possible that two rolls of film that have different dates of expiry could be from the same master roll?

I belive so, when Neopan 400 was running down, I did get some rolls with different dates but the same emulsion number. Not sure if they were from the same master roll, but from the same batch.

 

[MattKing]

Is it possible that two rolls of film that have different dates of expiry could be from the same master roll?

It is certainly possible that the date relates to the date of confectioning, as well as the date of coating.
Ian is correct - the specifications relate to the requirements for ISO certification. Part of that relates to issues in respect of packaging.