I have recently come across a few rolls of HP5 PLUS which expired 30 years ago.
Although I am not planning to make any miracles, I would like to try out the films since I have some chemicals approaching the end of their stock life.
Would anyone give me some advice on how much I should push the films and whether a longer development time would be required?
Just take a five shots in a row -- from ISO 400 down to 100 -- of a well metered scene. Develop normally. You'll have your answer. If they all come out took "weak", do it again, but increase the development time.
Much depends on how the film was stored during its life.
HP5+ ages badly unless kept cool. Not just fog but an uneven loss of response to light. As in, I'd say its curve changes shape. Anyway, it looks worse as every day goes by. You'll get not much to look at exposing at 100, unless it's been cold stored.
More grain, lower ability to get any shadow value, higher base fog, lower speed. Increasing development time makes the fog impenetrable.
I have recently come across a few rolls of HP5 PLUS which expired 30 years ago.
Although I am not planning to make any miracles, I would like to try out the films since I have some chemicals approaching the end of their stock life.
Would anyone give me some advice on how much I should push the films and whether a longer development time would be required?