Latent image fading

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tim.bowman
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Latent image fading

Post by tim.bowman »

Does anyone here have any data (or can point to any research) about latent image fading?

I read somewhere on the internet (APUG, perhaps, can't remember) that latent images on film/paper fade over time if you wait to process them. I convinced myself that I saw latent image fading in my larger format paper negatives, so I always process them the same day I expose them. Then a month or so ago, I tried a test for latent image fading on Arista Ortho Litho and didn't see any fading, even after the film sat for two weeks. Admittedly, I had some chemistry problems on the litho test, so any change would have to be pretty severe for me to notice.

Does latent image fading really exist? Or, is it like much technical photographic information on the internet, completely taken out of context and/or wrong?

Also, hope you're all getting some good darkroom time with most of us being asked to stay at home to avoid COVID-19.

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sanchell
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Re: Latent image fading

Post by sanchell »

Greetings, Tim.

I have never heard of latent image fading. That doesn't mean it doesn't exist.

What does exist is increased base fog that severely reduces sharpening. This is caused primarily by background radiation that is ever present, even in cold storage.

In essence, background radiation from the earth or atmosphere can penetrate steel lockers, freezer chests, etc. and continue to expose undeveloped film, with or without an image (think of x-rays at the airport; it doesn't matter if the film is exposed or not).

This is why long-term storage is not a good idea for optimum results. Though, admittedly, the build-up of fog caused by background radiation is a very slow process that is accelerated at higher temperatures. It is why film exposed during WWII and recently developed still exhibits an image.

The resulting image is not sharp, and with older emulsions there was a secondary effect not much seen today, grain migration, particularly with higher temperatures. The reason grain migration is not as evident is the increase in hardeners used by most manufacturers in order to facilitate machine processing. This prevents the emulsion from becoming soft, effectively preventing grains from migrating.
Do it in the Dark,



Steve Anchell

tim.bowman
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Joined: Mon Nov 07, 2016 8:55 am
Location: Winston-Salem, NC, USA
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Re: Latent image fading

Post by tim.bowman »

Thanks Steve. There's so much completely wrong information about film photography in the internet. It makes me wonder how many people who post have actually done any darkroom work.

By the way, thank you once more for the Darkroom Cookbook. This week, I rescued a box of lightly fogged paper by adding a bit of potassium bromide to the developer. Worked like a charm. I wouldn't have known to do that if not for the Cookbook.

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sanchell
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Re: Latent image fading

Post by sanchell »

I was speaking with Timothy Stearman yesterday. Timothy's company, Stearman Press, markets daylight developing trays and tanks for large format. He mentioned that many of his customers are young photographers who are struggling to teach themselves, for lack of darkroom courses in school I assume, how to develop film. I have no doubt, though this was not discussed, that many of them are posting their new found skills on the web without fully understanding the process.
Do it in the Dark,



Steve Anchell

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