Hi all,
Thanks again for the feedback. I figured an update might be useful.
I had another roll of FP4 to develop, and I hit the same problem again :-( I shot it on a trip to a different island. I was as careful as I've ever been with the development, and did 6 rolls of 35mm FP4 beforehand, with exactly the same setup. I used fresh fixer and stopbath, mixed the rodinal minutes before use, filtered water through a Brita filter, and was really careful with times and temperatures. There were no speckling issues with the 35mm film. Nor were there issues with the Retro 80S or Delta 100 120 film from the batch with the first problematic roll.
Dead Link Removed
(Inishmore, largest of the Aran islands.)
This leads me to believe that it is caused by bad film, i.e. as Tony and Rapael mentioned, a combination of backing paper and storage conditions affecting the film before exposure. In the case of TMAX, I could pretty much guarantee this by the presence of the frame numbers and 'KODAK' all over the negs. Those negs also had mottling too. I also had the effect, as mentioned, on some rolls of Pan F earlier in the year. In retrospect I can add one lab-developed roll of Portra 160 (at the time I assumed the lab made a blunder)
here's an image of the backing paper- is that the same speckled pattern?
Dead Link Removed
I still have 4 rolls of FP4 left, but I'm not sure what to do with them. As per Murphy's Law, on frame 6 of that most recent roll of FP4 my Hasselblad properly jammed and I had to send it to the UK where hopefully it can be fixed/serviced. I can't do any tests but may do in future. Oddly it meant that I didn't spend lots more time taking speckledy photos on islands.
I know with the TMAX there is a batch number on the negative (near frame 11) and I could see that my remaining rolls were from the same batch so I put them aside.
The developed negatives of both damaged FP4 rolls have "4296" printed along the edges, while the remaining rolls have "31AFN1C01/01 JUL 2019" or "37EFN1C02/03 JAN 2020" on the boxes. I don't have the boxes for the shot rolls :-( I wonder can I figure out if the 4296 indicates which batch they were from? I think probably the 2019 ones, simply because there are more of them left.
Dead Link Removed
I have dug up a lot forum posts with similar issues; one idea I have is that the supplier is/was storing film in a fridge, which may be causing moisture buildup.
I wonder is it worth sending the film to Ilford? If/when I get the Hassy back I could buy another roll of FP4 from a different supplier, then shoot them all, and develop them as I have been. It might confirm/refute my hypothesis. I guess that will only be mostly for my own peace of mind.
Hopefully onwards and upwards from here.