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Tim Hyde
3-Apr-2006, 09:48
I am wondering if handling film while cutting (I cut 8x10 sheets for my 5x7) or putting it in the film holder or removing it from the film holder is a problem. Tuan in his 5x7 piece mentions that finger prints wash off during developing. Other people talk about using surgical gloves during these processes. So, what's the verdict? It can get hot in the changing tent and I know I'm leaving finger prints on unexposed and exposed-but-undeveloped film. Mostly the prints would be around the edges, but is this a problem?

Aaron van de Sande
3-Apr-2006, 10:04
I had just this problem with efke25 in rodinal. Fingerprints in the skies until i started wearing cotton gloves. I think the developer/film combination probably determines if this is a problem or not.

Donald Qualls
3-Apr-2006, 14:48
What you've been eating also affects this, believe it or not.

Some years ago while working (briefly) in a blueprint shop, I discovered, after gorging on homemade onion rings the night before, that my perspiration, as carried on my fingertips, would develop the blueprint paper (normally developed by anhydrous ammonia in the printing machine) -- leaving blue finger marks on the prints, which wasn't very popular...

A number of years later, I found that something similar left a lot of fingerprints on a roll of microfilm I had loaded for my Minolta 16 (prints are very visible when a single print is larger than the image frame). Yet I've also seen identical handling have no effect.

What I think affects things (other than the number of onions in your recent diet) is how sweaty or oily your skin is when handling the film (sweat, like any liquid, can locally desensitize film causing low density print, while oil can repel developer), how long the print will remain on it (a print left before storage and exposure has more time to affect the gelatin and halide, while one applied immediately before processing is more likely to simply wash off in the alkaline developer), and as suggested above, the combination of film and developer in use. Best to avoid the problem: at a minimum, wash your hands with mild soap and dry thoroughly on a clean towel just before going dark to handle film (I can't use gloves, they reduce sensation too much for handling film), and don't touch your face while in the darkroom (usually the oiliest part of your skin, and often the sweatiest that's exposed when you're dressed).

paulr
5-Apr-2006, 09:05
what you dip your onion rings in also makes a difference ... ketchup or anhydrous ammonia? :-)