In depth understanding of the developing technique of the very old latent image

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Eugen Mezei

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The thematic of found film was discussed thousands of times. My problem is, people use what they have at hand and are confortable with it, the basic idea being, that either an image will come out or not, so it is not worth investing a lot of effort. My philosophy goes the other way; if an image survived latently for such long time, I am willing to to my very best and invest a lot of effort to rescue it to its best condition.

Until now I developed my own negatives I kept for 12-14 years in the freezer. But now I found a roll film of Perutz Perpantic 18, meaning it is from the 1950s, and around 25 sheets of different emulsions that came with holders for a Graflex, which I think are even older. (Needless to say, different to the rolls I exposed myself it is unknown how these were kept.) I also have some newish cinematic rolls exposed in the 70s.
My intention is, to discuss the parameter and their interaction that influence how much of these very old latent images can be rescued at the hightest quality. It should be exclusive about black and white negative film. This is what I thought about has an influence, feel free to add more:


1. Developer
It seems that when thinking further than using what is at hand the basic idea is to bath the film in a developer that inhibits fog and avoids coarse grain. For the first often HC-110 is recommended and for the second parameter often Rodinal is said to be avoided or to be used at high dilution. Also for low fog I saw others recommended like D23.

Then another problem I thought is important is the film-developer combination. To my surprise even companies/organisations specialising in rescuing found film (like the ones where you can send in your very old roll of film, e.g. filmrescue.com) use one single developer and develop multiple rolls in one go. I am not sure this gives the best reachable result but a compromise.

Which developer do you think restrains fog the best? Which delivers the finest grain and best sharpness with old film?



2. Dillution
My understanding is, that the developing process should be as short as possible to avoid fog. High dillution contradicts this, but has other advantages, I did not completly understood. (Grain, accutance?)


3. Agitation
Often stand developing is used, I think for security. (Something will show.) But it also increases fog.
If stand, which would be the best developer and how far to go with dilution?
Others say agitate as vigurously as possible, again to keep time short and therefore avoid fog.
Also it raised the question if we want increased contrast (vigurous agitation) or is it either contraproductive for old exposed film.


4. Temperature
Low temperature = low fog. I myself used Stöckler and D23 as Metol is still active at very low temperatures (I did go down to 9 degree Celsius.) Hydrochinone stops developing at low temp.

What other active agent is recommended, what other recipy suits low temperatures and how low is usefull to go? Going lower also increases the development time.



5. Fog restrainers
KBr and Benzotriazole are the classic restrainers, although I saw others too. (e.g. NaBr and different derivates of Benzo.) I read some study about how the two act differently, my understanding is, that Benzo would be the better choice for film kept very long.
Which one and how much to use? What is too much and how it exercits a negative effect?



6. Time
Loooong stand development at one end, continuuous agitation at the other. Between semistand, rare intermitent agitation, heavy agitation. Which one and how to weight the parameters it influences applied to our specific situation of the very old latent image?



7. Film-developer combination
General rules? Are the recommandations of the producer for the fresh film of any use?



I guess what I would like to do is understand what and in which direction influences the different parameters and after that to weight (as they work agains each other) the parameters in regard of the purpose of producing the best quality from that very old latent image.
 
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ic-racer

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Like many aspects of film photography; trial and error.
 

Alan Johnson

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(5) This article describes the use of Benzotriazole:

(1) The previous ,viscous, HC-110 was often recommended, it seems that users found it to be effective.
This could be because it contained the PVP antifog ingredient.
So far there seems to have been little discussion of the newer water based version.
 

chuckroast

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I cannot speak to film with latent images on it, but I have shot and developed film that went out of date as long ago as 1961. i.e. I just added the latent image recently to very old film.

I got entirely reasonable images doing this with semistand development for an hour using both D-23 and Pyrocat-HD without any special restrainer or other change of methodology beyond the usual ones I use for all semistand; Suspend the film minmally and raise it well off the bottom of the developing tank.

The larger issue I found was physical deterioration of the film - emulsion chipping, sheets sticking together - that marred the images.

In general, the D-23 produced more grain, but lower overall fog. Pyrocat-HD masked the grain better but showed somewhat more evidence of fogging.

Examples here:


It's worth noting that SuperXX was an inherently grainy film in the first place.
 

Bill Burk

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You say you have found a lot of film which has exposures on it that you want to recover.

Try to get an infrared scope/viewer. The technology which used to be out of reach is available literally in toys.

Cut tiny pieces of film off your found film and develop those experimentally.

Fog is the biggest antagonist in old latent images and that’s compounded by loss of latent image over time. You really have a delicate molecular structure that you want to reveal before fog wipes it out.

Cold, concentrated developer (developer that would work fast if it was warmer) is what I would try first.

I would avoid anti-fog agents such as Benzotriazole or Potassium Bromide because they cause loss of speed. That is fine to restrain fog of fresh exposures on old film that you can adjust according to results.

But you have old exposures on old film where someone assumed a certain speed and exposed accordingly. So no restrainer.

Hit it hard with strong developer but keep the developer cold so you have working time. Develop by inspection, with infrared viewer. If the film is orthochromatic or blue-sensitive, then you can use a red safelight. But you want to snatch it when the image appears before the fog wipes it out.
 
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Eugen Mezei

Eugen Mezei

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You say you have found a lot of film which has exposures on it that you want to recover.

Try to get an infrared scope/viewer. The technology which used to be out of reach is available literally in toys.

Cut tiny pieces of film off your found film and develop those experimentally.

Fog is the biggest antagonist in old latent images and that’s compounded by loss of latent image over time. You really have a delicate molecular structure that you want to reveal before fog wipes it out.

Cold, concentrated developer (developer that would work fast if it was warmer) is what I would try first.

I would avoid anti-fog agents such as Benzotriazole or Potassium Bromide because they cause loss of speed. That is fine to restrain fog of fresh exposures on old film that you can adjust according to results.

But you have old exposures on old film where someone assumed a certain speed and exposed accordingly. So no restrainer.

Hit it hard with strong developer but keep the developer cold so you have working time. Develop by inspection, with infrared viewer. If the film is orthochromatic or blue-sensitive, then you can use a red safelight. But you want to snatch it when the image appears before the fog wipes it out.

I will look for a toy viewer, hope they are tight. (As I understand in fact you have a webcam without IR filter and a tiny screen built in a google.) They are not usual here, but maybe from abroad I can get one.
No, unfortunately all the films I have are panchromatic. I thought about developing them by (short) inspection with a very dark green filter, as it is described in literature, but I think it will be not very usefull and just very risky.
 

koraks

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Consider that when trying to cut fog on expired film, the problem is that you end up cutting into shadow detail as well. The two overlap; density is just density and silver halides don't care whether they have become developable due to exposure to light through a lens, background radiation or some other factor. There's no way to chemically select out the age-related fog from actual image density.

So I would in fact not add any additional restrainers at all, and instead just develop, scan and then salvage whatever images on there digitally. If the negatives turn out to be printable optically, that's great, of course.
 
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Eugen Mezei

Eugen Mezei

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Consider that when trying to cut fog on expired film, the problem is that you end up cutting into shadow detail as well. The two overlap; density is just density and silver halides don't care whether they have become developable due to exposure to light through a lens, background radiation or some other factor. There's no way to chemically select out the age-related fog from actual image density.

As I understand the developer "attacs" first the silverbromide crystals that were hit by photons.[1] But if the emulsion is left too long in the developer, it develops the crystals not affected by light, producing fog. So the trick is to develop all the affected crystals but stop just right before beginning to get silver out of the crystals not hit by light.

Are you sure we cut into shadow detail, not into highlight detail? My thought is that highlight will be developed first, being the regions containing more silver.


[1] Or any radiation interacting with the electronic balance of the crystal. So you are right it does not matter by what means the crystal became developable. Therefore we can not not develop the crystals that became developable in time. The best we can do is to avoid overdeveloping.
 
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Eugen Mezei

Eugen Mezei

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The basic idea being not to overdevelop, how I have to handle the following parameters?

- preash; Will the developer penetrate the emulsion faster? Is this true at low temperatures?

- alcalinity; Higher pH better? it sure will accelerate the development, but also cause bigger grain.

- splitted developer; Developing in low pH and immersing the soaked emulsion into an alcaline solution.

- Methol; Does not stop working at low temperatures. Has a high temperature coefficient, meaning the colder the developer the very much longer I have to develop. Develops highlights first but than has difficulties building density. Is also not affected by bromide.

- Hidroquinone; Stops working in cold. When it works has not a high temperature coefficient, meaning temperature changes doe not cause big changes in developing time.

- splitting MQ; What if I first develop in Methol to get the highlights and than develop in a separate solution of Hydrochinone for the shadows?

In literature I found contradictory information. Some book states Methol being relatively insensitive to the pH (and being happy at pH 8, that can be reached with sulfite) and Hidroquinone being much more affected by alcalinity. Other authors say exactly the opposite.
 
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loccdor

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In 2011 I was offering a black and white developing service as an odd job while in college, the highlight was some 35mm film from a Romanian customer's father, he didn't know what was on it - it turned out to be pictures from the overthrow of the Romanian government in 1989. I think I used HC-110, as it was my go-to developer and also recommended for fog/expiration... the pictures came out reasonably well, the biggest negative effect on them was that the metal cassettes from that country weren't completely light-tight on the end-caps, so there was light leakage near the sprocket holes that occasionally went down a bit into the picture area.

1989.jpg
 
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Eugen Mezei

Eugen Mezei

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Another idea that occured to me: Is presoaking good or detrimental in rescuing the latent image?
 

Romanko

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My intention is, to discuss the parameter and their interaction that influence how much of these very old latent images can be rescued at the highest quality.

This would make a good subject for doctoral thesis on the theory of photographic process.

I am by no means an expert but I've done a bit of "found film" rescue and here are my thoughts:
1. The developers can be characterized by their activity: the ratio of latent image developing speed to fog forming speed. This might or might not be related to the "film speed" achieved by different developers.
2. While fresh film is developed to the desired contrast, old film is best developed to the maximum ratio of negative density to fog density, which might be different. So a popular advice to "develop to higher contrast" might not always be correct.
3. There is some evidence that cold development produces less fog but only with some developers.
4. For developers using several super-additive developing agents the effect of temperature could be really complex as each agent has its own temperature dependence. Technically, when going well below the normal temperature range of 18-24 degrees Celsius you are dealing with a different developer.

The idea of a perfect developing technique for old negatives is certainly attractive but the reality is that forgotten film most likely have no historical or artistic value. No photographer would leave an important negative sitting in the camera for 50 or 70 years. Also, the storage conditions and emulsions are so different that it might be impossible to design a technique that works equally well for all negatives.
 

guangong

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Several years ago the British Film Institute processed movie film discovered in Antarctic from a 1912 expedition. Perhaps you could make an inquiry about how they accomplished this. If memory serves me, I believe negatives for still pictures were also discovered.
 

loccdor

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No photographer would leave an important negative sitting in the camera for 50 or 70 years.

While most forgotten negatives are not remarkable, just as most fresh negatives are not remarkable, it does occasionally happen, sometimes to an extreme degree. People may become ill, die, be forced to quickly relocate, have their possessions stolen or confiscated, etc. Or, sometimes people just want to start a new life and forget their old one. Why wasn't this film cassette of a historical event not developed until 30 years later? I don't know. Perhaps it was left in an old house, the family left the country for a new one, and then only discovered it on going back after many years.
 

juan

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A couple of years ago, developed Tri-X shot in 1972 in dilute FX-2. Developed for one hour with agitation about every three minutes. The shots outside in sunlight came out fine. The interior shots had little in the way of images, but I have no idea how much exposure was given.
 

john_s

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A couple of years ago, developed Tri-X shot in 1972 in dilute FX-2. Developed for one hour with agitation about every three minutes. The shots outside in sunlight came out fine. The interior shots had little in the way of images, but I have no idea how much exposure was given.

I'm curious. Did you have a particular reason to use FX-2? It's easy to mix as long as you can source the glycin which isn't locally available.
 

juan

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I had glycin and metol. FX-2 more or less develops to completion when used for an hour with a minimal agitation scheme. I didn't have a way to test, so I figured this would give me the best shot at getting an image.
 

Jojje

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- preash; Will the developer penetrate the emulsion faster?

On the contrary: developer will work slower with emulsion which already is wet. If prewashing, add 30 seconds or so to the developing time.
 

chuckroast

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Several years ago the British Film Institute processed movie film discovered in Antarctic from a 1912 expedition. Perhaps you could make an inquiry about how they accomplished this. If memory serves me, I believe negatives for still pictures were also discovered.

Was this from Shackelton's ill fated trip on the Endurance?
 

loccdor

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On the contrary: developer will work slower with emulsion which already is wet. If prewashing, add 30 seconds or so to the developing time.

That makes sense! Just like a dry sponge absorbs water faster. But it was the first I have ever heard of it.

Now it makes me wonder about all those dev times on Massive Dev Chart. They never specify if they prewash or not, so it's another reason why they're just "in the ballpark" at best...
 

chuckroast

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That makes sense! Just like a dry sponge absorbs water faster. But it was the first I have ever heard of it.

Now it makes me wonder about all those dev times on Massive Dev Chart. They never specify if they prewash or not, so it's another reason why they're just "in the ballpark" at best...

I may be wrong, but as I recall, prewashing was historically done to make developer infusion more even, not faster. There's been a lot of debate about its value and efficacy. I've done it for years, and it certainly does no harm (so long as the prewash temp matches the developer temp closely). The only reason I still do it is that I am loathe the fiddle with working darkroom processes.
 
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