What process should I use for developing old (Ferrania?) CR50?

Question

I have some old film cans which are marked as 'exposed' and 'CR50'. From what I can tell, this is most likely to be Ferrania CR50, but that's an assumption.

I've done a fair bit of B&W developing (mostly of 16mm cine film), and having read about developing colour reversal film as B&W I decided to give it a go - using Ilfosol S, Ilfostop & Ilfofix just as I've done with some old FP4 cine film.

The result on the first CR50 film was disappointing - nothing on there. I can make out a slight darkness change between the film that was inside the can and the small amount poking out the end of the can that was exposed to light - so I guess I've 'developed' something.

But can anyone tell me a better way to develop this (as colour, or B&W). I can't seem to find any reference to what process it needs.

---- UPDATE ----

My film scanner found nothing on the film - and even I was pushed to see anything other than possible 'smudges'.

Then I looked again at the top edges with a magnifying glass, and I can see, quite faintly, 'SAFETY' in a few places. So, it does appear to have developed - but perhaps the original pictures were very underexposed as there's really nothing to see.

I'll increase the developer concentration and temperature for the next can (I have 4 more). It's good to know I'm on the right track and the comments below reassured me enough to look again at the film.

Answer 1

Some searching seems to indicate that that particular film dates from about 1970 (apparently the "Ferrania" brand name has changed owner at least once), see e.g. here. And this thread makes me suspect it might require the E4 process for development.

Note that if the film dates indeed from the 1970s (or before!), any exposition from that era might have faded by now, in part depending on how the film was stored.

See also this question and this thread on photonet, concerning fading of exposed, but undeveloped film. And there is a company filmrescue that specialises in developing old exposed film

Another complication might be that the actual ISO value could differ from the stated ISO value (and that at least one company sold that film as a 64 ASA film), so the film could have been underexposed to begin with (by a stop or more)

Answer 2

Well I'm answering my own question as I had some more old reels of film to develop and so was able to experiment a bit - and the results might be useful to other people.

All the below are colour reversal films developed as B&W, using Ilfosol 3 developer (1+9 dilution), Ilfostop (1+19 dilution) and Ilfofix (1+9 dilution). All at 20 degrees celsius.

In all cases, Ilfostop was for around 30 seconds and Ilfofix was for 7 minutes.

Obviously I don't get any colour from them - just monochrome. There was a green tinge to all of them, except the magenta & cyan ones mentioned below.

Ferrania CR50 (35mm): 8 minutes. All the films I developed had never been exposed, but I got to this time from developing the word 'SAFETY' on the film edge :-)

Kodak Ektachrome EPD135-36 'Process E-6' (35mm): 6 minutes gave an underdeveloped result - so I'd shoot for 7.5 minutes if done again.

Kodak Ektachrome EH135-20 'Process E-4' (35mm): 8 minutes gave an overdeveloped result - so I'd go for 6.5 minutes in future.

Kodachrome-X EX620 'Process E-4' (120 size film): 6.5 minutes gave a good result.

Kodakcolor 400 'Process C-41' (120 size film): 8 minutes - turned out very well. Had a magenta finish, which partly washed out into the developer & fixer (which helped the scanning). Easily the best result I had.

Agfacolor CT18 (120 size film): 8 minutes - good results, a strong cyan finish washed out into the developer & fixer.

I also developed some colour 16mm cine film using the same process:

Ektachrome EF7242: 8 minutes - good results.

Agfa Gevaert T615: 8 minutes - good results.

Most of the films were around 35 to 45 years old - so it was good to see what was on them.

Thanks for people's comments on this.