Fingerprints on negative

I recently printed a few contact sheets (from 4x5" sheet film) and then noticed what appears to be fingerprints on one of the negatives (see image attached, to the left and right and just below the horizon). It looks like the marks are in the emulsion. I am a bit puzzled since the marks have built extra density compared to the background; I would expect greasy fingerprints applied pre-development to result in developer not reaching the emulsion end hence less density. Can greasy fingerprints applied post-development somehow build extra density to the emulsion? Most importantly, is there some way to remove the marks? I tried to gently rub the negative with a cotton ball soaked in IPA, without success...

@henpe I cannot help with your question, but wanted to say this photo is absolutely superb.

Any chance that the fingerprints came from the contact printing frame?

MattKing said:

Any chance that the fingerprints came from the contact printing frame?

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I am afraid not! The marks appear to be "burnt in" into the emulsion and I suspect they will be there to stay. It's a pitty, because I would like to make a print out of this one and I am not sure I am skillful enough to spot a potential print without leaving too obvious traces.

I guess I should just leave this negative and move on. But I am still curious to find out, can fingerprints react with the developer and either catalyst its activity or react with it to form some kind of opaque compound? Seems like it!

Bormental said:

@henpe I cannot help with your question, but wanted to say this photo is absolutely superb.

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Thank you Bormental. I like this scene myself. The island you can see in the horizon is quite famous here in Sweden. An old story-tale says that all witches fly there (on their brooms) on Easter eve night for a big gathering...

Could it be from "dirty" fingers when removing the wet film from the spiral/tray/tank?

Mike

mpirie said:

Could it be from "dirty" fingers when removing the wet film from the spiral/tray/tank?

Mike

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Could be! If so, will this leave a permanent etching/mark or is there a way to clean it off?

Usually trace amounts of developer on the fingers will do this, but I've only seen this due to insufficient hand washing during development or contaminated counter tops. Placing a damp hand on a contaminated surface can pick up residue and transfer it when unloading film hangers, tanks or whatever you use to develop the film. It only takes a tiny amount and it cannot be reversed in my experience because it is developed silver and is now part of the image.

You could try spotting the print if the image is of sufficient importance to you...

henpe said:

Could be! If so, will this leave a permanent etching/mark or is there a way to clean it off?

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If the markings have dried in to the point where you are printing from it, then i doubt it'll be removable.

Like Kino says, it depends on how important the neg is to you.......if it is, spot the print.....if it's not, try washing the neg again and see if the marks will come out?

Mike

mpirie said:

try washing the neg again and see if the marks will come out?

Mike

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+1. It's always worth a try. Use tepid water with a tiny drop of wetting agent and let the emulsion soak for a few minutes.

Another possibility (for the origin of the prints) is that something else on your fingers locally increased the activity of the developer during processing. I once had a problem (during a brief tenure at a blueprint shop) after eating a lot of onion rings the night before; there was enough of something in my sweat or skin oil to make fingerprints on the commercial blueprint (diazo) paper. At the time I thought it was probably an ammonia compound of some kind, since that paper was developed with anhydrous ammonia.

The same thing (ammonia compounds in your sweat from eating onions -- or thiosulfate from the onions, which is also a foggant, not just a fixing agent) could have affected the emulsion. Local chemical fogging would indeed be permanent, and would show as extra density (light on the print).

I don't develop my own. Curious about handling though. I just started with 4x5 both Velvia 50 and Tmax. I've been using gloves but also tried without gloves and washing my hands to remove any skin oils and trying to hold carefully. Has anyone actually seen problems without gloves that show up when scanning or printing handling processed film after the fact?

I've got several .EDU 400 (Fortepan rebranded) 4x5 and old Tri-X 320 9x12 negatives that show fingerprint marks as well as other spots of unknown origin, but they sat in film/plate holders for around twelve years. Puts an upper bound on it, though -- even with clean hands, fingerprints will show as changes in local emulsion sensitivity after a decade or so.