Developing Unknown Film

<p>I bought a used Alden bulk loader and it's heavy with a spool of film. I like shooting odd duck or expired film. I removed 6" of film and fixed it in TF-4 but did not see any markings on the edges that would identify the film.</p>

<p>How do I proceed to determine the film's effective speed and developing time?</p>

<p>Thank you,<br>

Jim</p>

 

The film still needs to be developed to reveal

any edge marks.

 

I'd shoot a short test roll, develop it for

around 8 minutes in D76 or ID-11 @ 1+1 dilution,

and evaluate from there. Any standard developer

for a typical developing time will do.

 

Combined with bracketing in full stops, Diafine

can be handy for identifying unknown film, but

isn't ideal for expired film - it tends to

exaggerate base fogging.

 

That's what I did to help find an appropriate

exposure and development for a completely

unmarked bulk roll. No edge markings at all. It

resembled Ilford Pan F in speed, etc. No idea

where it came from.

<blockquote>

<p>I removed 6" of film and fixed it in TF-4 but did not see any markings on the edges that would identify the film.</p>

</blockquote>

<p>Fixer removes silver salts that have not been converted to silver solids by developer. Take another strip of film and develop it in any standard strength developer for 6 minutes at 68°F then fix. This will give you the edge markings.</p>

<p>Thank you, Lex & Charles. It never occurred to me that the edge markings had to be developed. I assumed they were ink-printed onto the base.</p>

<p>Your suggestions for standard developing times has be wondering if a two-bath developer would be ideal. I have Pyrocat-HD but it's not so good for old fogged film.</p>

<p>Thanks for the suggestions! This could be fun.</p>

Be sure to keep your test strip out of the light or all you'll get is black, no edge markings.

<p>First thing is to develop and fix a short strip -- six inches or a foot will do. That should tell you exactly what kind of film it is from the edge markings.<br /><br />If it doesn't have edge markings or not ones you recognize, I would do a variation on what Lex said. Go outside at mid-day with bright sun behind you and shoot an "average" subject maybe even with a gray card in the photo. Follow the sunny f/16 rule and set your aperture at f/16. Then do a series of shots starting with the shutter speed at 1/30 and go all the way up in full-stops to at least 1/500, maybe 1/1000. Keep notes of which frame is which. Develop the film in D-76 or ID-11 and see which frame gives you correct exposure. Take note of the shutter speed for that frame, and that will give you the approximate ISO.</p>

<p>I developed an unexposed strip tonight. There were no edge markings. The exposed leader was completely opaque, as would be expected, but the unexposed area was extremely dark.</p>

<p>I developed it for 10min in DD-X(1+4), stopped, then fixed for 6 min.</p>

<p>Sooooo, I guess this film is unusable which is kind of a surprise.</p>

<p>No edge marking, FP4 maybe?</p>

<p>Ok, so I did a test with 15+/- frames, opening stops rather than adjusting the time. Apparently I had not developed a long enough roll, previously, to see the edge markings. This time I saw two sets of edge markings identifying the film as Tri-X. My test indicate that this old roll is EI 50. It has a <em>lot</em> of fog to it but is usable. It's about the grainiest film I've ever seen. I'll can it and keep it around for tests.</p>

<p>Thanks for your help!</p>

<p>HC 110 at 65°F will reduce fog by 50% or better. At ISO 50 increase published development times in HC 110 by 60%. I had some that the image was not distinguishable from the fog when exposed and processed normal but produced a usable image at this modified development.</p>