developing old film

[Augenblick]

I've found a few rolls of HP5 the other day that were exposed (at 400ISO) 20 odd years ago. How much would you recommend extending development times over the normal? The film has not been kept in the fridge. Thanks.

 

[Joao]

I am not able to recommend a precise developing time in those conditions. It will be difficult to calculate - and depends on the developer.
I sugest you a Rodinal stand development. I worked for me for unknown films of unknown age kept in unknown storage conditions.
Good luck
Joao