What exactly happens to "outdated" film anyway?

[Daniel Grenier]

This is something I have never quite fully understood. What exactly happens to (unexposed) B&W negative film over time and what is the rate of "decay" ? Also, how conservative (or optimistic) are the best-before dates on B&W film these days? I know that FB+F increases but what else is going on ?

Also, I bet that 6, 8 even 12 months after the indicated date the film is very likely unchanged (if stored normally). Is that a fair assumption ?

 

[Dave Parker]

Hi Daniel,

I have shot out of date film for years, with proper storage, the most noteable thing I have noticed is a change in actual speed of the film, I have never noticed shifting in the shadow areas and such as others have reported, the last box of 4x5 film I shot has been stored for many years, we did see a small amount of fogging on a few sheets, but for the most part, it rendered nice tone and such....expiration date was 1971...of course I am sure there are many others out their with different experiance..

Dave

 

[Konical]

Good Afternoon, Daniel,

There are some APUG members with lots of photochemical knowledge who can probably answer your basic question with a degree of precision which I certainly lack. I understand, however, that cosmic rays will inevitably cause fogging of film regardless of how it is stored.

In practical terms, your bet is right, at least in my experience. In fact, I think that you can change the "months" to "years" with most B & W films, even if storage is in less than optimal conditions. If you freeze the stuff, you're probably going to see almost no change for decades. I've used 25-year-old Tri-X kept at room temperature and experienced very obvious fogging; I've also used slow copy film (Kodak Commercial) which was kept at room temperature for over 15 years and found it to be good as new.

Signing off now to let those who have real knowledge of the topic chime in. (A SEARCH will also get you various postings on this topic.)

Konical

 

[David A. Goldfarb]

Past-date film will gain base fog, ultimately reducing speed and contrast range and increasing grain. Past date color film will do this unevenly, causing color shifts as well. Many E-6 films seem to go magenta.

Cold storage helps a lot. Slow films fog more slowly than fast films. B&W holds up better than color, because color shifts are not an issue with B&W. Neg film holds up better than slide, because you can correct small shifts in color or contrast in printing.

If you want to see some examples of really past-date film, I've posted some in this thread--

(there was a url link here which no longer exists)

 

[nick mulder]

I've got 20,000 ft (actually make that 19,200 ft after today) of Plus-X reversal film from the 60's in my new film fridge - I had some unexposed film tested for base fog at the local lab, just as good as film bought today apparently -

its a 50asa stock and it has been refrigerated most of its life tho...

 

[gr82bart]

Like most drugs in tablet form, I have always felt that "shelf life and expiry dates" are mostly a marketing creation. This might not hold true for film, but who knows?

I too have very old film that MY FATHER bought when he was doing his PhD in Germany in the 60s, before I was born, sometimes refrigerated, that I have used and if there was 'base fog' I didn't notice it. I still have 6 more rolls.

Art.

 

[Gerald Koch]

I have some Ilford Pan F+ that is 10 years old and was kept refrigerated. It shows noticeable fog and has lost half of its speed. My personal experience has been that Ilford films do not age gracefully.

 

[Tom Stanworth]

I have some Ilford Pan F+ that is 10 years old and was kept refrigerated. It shows noticeable fog and has lost half of its speed. My personal experience has been that Ilford films do not age gracefully.

Anyone notice that Agfa APX100 had very very long dates on? I wonder why? I had some that was mid 2009 bought at least 6 months ago. Sadly it is all gone.

 

[Photo Engineer]

Giving you a small window into emulsion making, one of the steps is 'finishing' or 'chemical sensitization'.

During this step, a sulfur compound such as thiourea is added to the emulsion and it is heated to 60 degrees C for about 1 - 2 hours. The reaction is then terminated by adding a restrainer such as benzotriazole or something like that. During this process, a given grain can gain several stops in speed.

If you overdo this process, you get less speed, and lots of fog.

The trick is to sell and use the film between the time when you have the best speed/fog ratio and before the natural warmth that film is exposed to causes the process to start over (such as in the glove compartment of your car). So, film will die a 'heat death' if kept too warm for too long. You can slow this down by keeping film cool or frozen.

Radiation will also cause the same effect, but cannot be stopped by cooling the film.

The faster the film speed, the more sensitive it is to heat and radiation. In practical terms, this defines the fastest a film can be and still be 'salable'. I believe that figure to be about ISO 3200 - 6400 for B&W. It is my understanding that the fastest film speed ever achieved was ISO 20,000, but the film would have been quickly rendered unusable due to the sentivity to heat and radiation.

Old films with ISO speeds of 100 or less apparently keep quite well, as do some printing papers such as Azo. Keep in mind as well that these were often stabilized with heavy metal salts such as mercury and cadmium which don't decompose with time, but the newer films are stabilzed mainly with organic compounds which do decompose with time. Therefore, modern films and papers are more environmentally friendly, but may keep less well than some older films and papers.

This is not a simple problem for the engineer.

PE

 

[PeterB]

Gamma rays will always get them in the end

Radiation will also cause the same effect, but cannot be stopped by cooling the film. PE

In an effort to better quantify an answer to the question posed by the OP which comes up so often, I am trying to measure and predict the (long term) fogging effects of gamma radiation on film and paper. To do this I need to measure the amount of background gamma radiation in my freezer. The energies of most gamma ray photons are sufficiently high so that

"there are, on the average, 5 to 10 grains made developable per photon interaction at high energy." [1]

Does anybody have any experience in measuring the amount of gamma radiation at particular locations on the earth? Geological survey folks do this from aeroplanes to detect certain radioactive elements in ore deposits. I am trying to toss up between trying to get my hands on either a Geiger Counter, or a specialised gamma ray detector that uses Thallium activated Sodium Iodide crystal or a Germanium crystal (Ge requires liquid Nitrogen cooling).

regards
Peter

[1] http://www.kodak.com/eknec/documents/87/0900688a802b3c87/Radiography-in-Modern-Industry.pdf page 205.

 

[wilt]

Found some Tri-X stored for 3-4 years in room temperature. Result: severe fogging.

 

[Photo Engineer]

Peter;

Gamma rays are not photons.

To get a handle on this problem you must first distinguish between gamma, beta and etc types of radiation and between radiation (gamma and beta etc) vs light.

I think that there is some lack of understanding here.

PE

 

[poutnik]

PE: gamma rays definitely are photons, only with much higher energy, therefore much shorter wavelength (inverse proportional relationship). You're right alpha and beta radiation is totaly different, those being helium nuclei (alpha) and electrons (beta minus). All of them can alter photographic emulsion. That is the way X-rays were discovered...

Jiri

 

[Dave Parker]

PE: gamma rays definitely are photons, only with much higher energy, therefore much shorter wavelength (inverse proportional relationship). You're right alpha and beta radiation is totaly different, those being helium nuclei (alpha) and electrons (beta minus). All of them can alter photographic emulsion. That is the way X-rays were discovered...

Jiri

You might want to take a look at the definitions of photons and gamma rays, seems there is some parameters on definitions of both types of energy.


http://en.wikipedia.org/wiki/Gamma_ray

Dave

 

[poutnik]

Sorry to bother, this is really about photography, not about the nature of photons. And I'm sorry I started with a rather negative reaction as my first post, prior to introduction. So to correct: I'm an amateur photographer taking the route from digital photography (which didn't satisfy me) back to the medium format and soon also to large format shooting. And btw. I just developed my third roll of film and it has photos I can look at more than once...

I admire all of you (counting PE too) for your photographic knowledge and mastery. No doubt here.

But on the physics side, you're (at least partly) wrong. Energy when transmited through the world behaves sometimes as particles and sometimes as waves. The particles are called photons. Photons of a certain energy have a wavelength on the order of 100 to 1000nm, where we call them photons of light (OK, from around 400 to around 700nm), if you move to shorter wavelengths, the energy goes higher and at one point we stop talking about the wavelength (what is a picometer to you anyway?) and start speaking about electronvolts (eV) because at this point the energy is really what matters. So, PE and Satinsnow, I'm pretty strong in the statement, that gamma rays are photons. And btw. if you look at the wikipedia description, the wavelength is described there too...

Jiri

 

[Ole]

I'm a "certified radiation worker", and measuring gamma rays is part of what I do for a living.

The only way to know what the radiation level is in your freezer is - to measure the radiation in the freezer. Sorry. In my job i measure the variations in natural gamma rays over centimeter scales!

And BTW: Gamma rays are photons. Beta and Alpha are not.

 

[Paul Sorensen]

I prefer to answer the original question: What happens to outdated film? Well, it all collects in the corner of my freezer, that's what happens!

 

[PeterB]

I'm a "certified radiation worker", and measuring gamma rays is part of what I do for a living.The only way to know what the radiation level is in your freezer is - to measure the radiation in the freezer. Sorry. In my job i measure the variations in natural gamma rays over centimeter scales!
And BTW: Gamma rays are photons. Beta and Alpha are not.

Thanks Ole, I mentioned that in my post "To do this I need to measure the amount of background gamma radiation in my freezer". So my question still stands, what tool would you use to do this?
Thanks to you (and Jiri) for reinforcing my assertion that Gamma rays are photons.

Peter

 

[Dave Parker]

But on the physics side, you're (at least partly) wrong. Energy when transmited through the world behaves sometimes as particles and sometimes as waves. The particles are called photons. Photons of a certain energy have a wavelength on the order of 100 to 1000nm, where we call them photons of light (OK, from around 400 to around 700nm), if you move to shorter wavelengths, the energy goes higher and at one point we stop talking about the wavelength (what is a picometer to you anyway?) and start speaking about electronvolts (eV) because at this point the energy is really what matters. So, PE and Satinsnow, I'm pretty strong in the statement, that gamma rays are photons. And btw. if you look at the wikipedia description, the wavelength is described there too...

Jiri

I am not wrong or right, as for the most part, I don't have any knowledge of what you guys are talking about! LOL

But now if you want to talk about the molecular make up glass to achived a certain outcome, there I might be able to come up with some information, as far as gamma rays and photons, now we are out of my area of interest or skill, that is why I looked up the Winkipedia definition, for the most part, I don't care, but I do know in scientific circles making statements of absolutes is not always a good thing.

Welcome back to the dark side.

Dave

 

[PeterB]

Peter;

Gamma rays are not photons.

To get a handle on this problem you must first distinguish between gamma, beta and etc types of radiation and between radiation (gamma and beta etc) vs light.

I think that there is some lack of understanding here.

PE

I agree, unfortunately though it appears that you are the one lacking understanding. Did you take the time to read the reference from Kodak that I gave ? The very sentence implied that the high energy (photons) are gamma rays. More specifically, another sentence in that publication says (on p. 196) that "The agent that actually exposes a grain is a highspeed electron arising from the absorption of an x- or gamma-ray photon."

regards
Peter

 

[Ole]

... So my question still stands, what tool would you use to do this?.

I'd use a Thallium activated Sodium Iodide detector - because that's what I use at work. I'd have to borrow a portable one though - the ones I use are firmly mounted in 2-ton MWD tools to survive being used 4000m down in the ground...

 

[PeterB]

I'd use a Thallium activated Sodium Iodide detector - because that's what I use at work. I'd have to borrow a portable one though - the ones I use are firmly mounted in 2-ton MWD tools to survive being used 4000m down in the ground...

Thanks Ole. Are the portable ones 'easy' to come by? I guess I'd have to have to know the right people in a similar industry (in Australia), or maybe I could rent one for a day !
Could you point me to any reference articles that would help me make the most of using one?

Peter

 

[df cardwell]

I'd use a Thallium activated Sodium Iodide detector - because that's what I use at work. I'd have to borrow a portable one though - the ones I use are firmly mounted in 2-ton MWD tools to survive being used 4000m down in the ground...

Or use the film before it's out of date.


:confused:

 

[poutnik]

PeterB,

for a quick and dirty measure (and not so accurate) you could go well with a plain Geiger-Muller counter connected to a meter (voltmeter). And I think you could find such a one in any high school teaching physics. I know it's more suited for a comparison of radiation in different places than to measure the actual radiation exposure, but it's the simplest, quickest and cheapest way. I'm sure you can borrow a portable meter, they are the size of an overgrown palmtop computer. I would not buy it unless you're living near an uranium mine, nuclear explosion test ground or something similar...

Jiri