I have used some 40 year old HP4, but my problem was slightly different. My film was unexposed and I tried it out for fun.
The emulsion was quite foggy, but it was even fog so the images were still printable. Effective film speed was down a bit, but it still worked ok.
I can think of three problems here.
First the film is foggy so you will want to try and minimise that by picking a suitable developer. ID-11 / D76 and fine grain developers can encourage fog as can push processing ones.
Second the gelatin may have degraded or got mould in it. In this case processing the film can remove all the gelatin and send it down the sink (with the images!) leaving you with a clear blank film (yep, been there, done that!).
Both extremes and changes in pH and temperature forces the emulsion to expand and contract, helping it escape.
Thirdly the latent images may have disappeared, since he has stretched the advice of 'process the film as quickly as possible after exposure' a bit!
At the very least any effective film speed and development times will be pretty meaningless now.
I have heard of people using desensitisation dye and developing by safelight for ancient films that might have valuable stuff on them - but it is a professionals job.
Well this is where the fun starts!
If it was me I might use Kodak D25 because the pH is near neutral and this is less likely to take the emulsion off. I'd then use pure water as a stop bath (acid stop baths will stress the gelatine again) and then maybe a simple hypo fixer, keeping everything at a nice steady 20 degrees C.
But the next person to answer your post will probably say "No! Rubbish! That is the wrong approach, you need a developer that is well restrained to control the fog!"
They might be right, too. My old HP4 had no problems in the gelatine department so maybe that isn't the issue (depends how the film has been stored) but was foggy.
I actually used Kodak DK50 with my later rolls of HP4 for this reason. It is a squeaky clean low fog developer. It helped
a bit. But I had the luxury of more than one film, so I knew the gelatine was ok. Fog, under / overexposure / thin images you can maybe do something about after processing. If the emulsion goes down the sink, you can't do much!
I'm sure there will be many other suggestion, too
From my ancient Ilford manuals I can tell you FP3 was made from 1946 to 1968, was rated at 125 ASA and the quoted development time in D76 / ID-11 was 7 1/2 minutes for 120 roll film. Not sure that will still be accurate after 40 years!
It might give you a starting point, though.
Let me know how you get on, because someone has given me a box camera from before WW2 and it still has the orthochromatic roll film in it, so I will be having another go myself, soon!
Steve
