Degradation of Colour Film over Time

[ChrisGalway]

Is anyone aware of a scientific study of the change in colour film characteristics over time? Presumably companies have done this ... how else would they arrive at the "use by" dates printed on the packaging? ... but I'm looking for something factual in the public domain.

I realise there are hundreds (or more like thousands) of anecdotal stories about "how long colour film lasts", kept at room temperature, in the refrigerator, or in a freezer, but has there been a published study, even if it is just for one film type?

I suspect no such study exists in the public domain, but perhaps someone can enlighten me otherwise?

 

[koraks]

You mean, unprocessed and unexposed color film, right?

I'd suggest reading the posts by Joe Manthey on the topic of storing unprocessed film and factors affecting its shelf life. Here's a list of all of his posts; the relevant ones are easy to pick out: https://www.photo.net/profile/324525-joe_manthey1/content/?type=forums_topic_post

I don't think he ever referenced publicly accessible studies on the topic. They may or may not exist; all the good stuff is likely company confidential, insofar as it hasn't been lost in bankruptcies, reorganizations and office moves over the years. Maybe @laser has some hints, too.

 

[ChrisGalway]

You mean, unprocessed and unexposed color film, right?

I'd suggest reading the posts by Joe Manthey on the topic of storing unprocessed film and factors affecting its shelf life. Here's a list of all of his posts; the relevant ones are easy to pick out: https://www.photo.net/profile/324525-joe_manthey1/content/?type=forums_topic_post

I don't think he ever referenced publicly accessible studies on the topic. They may or may not exist; all the good stuff is likely company confidential, insofar as it hasn't been lost in bankruptcies, reorganizations and office moves over the years. Maybe @laser has some hints, too.

Thanks Koraks, I thought you might know! I'll follow up those posts by Joe Manthey.

 

[DREW WILEY]

There are a number of known variables. Proper frozen or otherwise cold-stored film lasts a lot longer than improperly stored film. Hot and humid conditions affect film life. High-speed films are subject to more rapid cosmic-ray degredation. Amateur films have lower expectations than pro film, so the makers take into mind that marketing distinction to begin with. The science of the dyes involved, in the case of color film, is quite complex and specialized;
so don't expect simple answers there.

But since manufacturers have no control over conditions once film leaves their own hands, the best they can do is provide helpful tips on their technical sheets. Have they actually studied these things? - undoubtedly. But attempting to quantify such variables outside a controlled laboratory setting, relative to actual user conditions, is always risky, leading to either misunderstanding or potential liability. They can't test for everything.

Now there are also questions about the long-term effects of 120 backing paper, potentially pertaining to recommended expiration dates. I have never personally encountered that kind of problem, but some apparently have.

 

[Steven Lee]

Once I found an old roll of unexposed 135 film in my parents archives. There were no markings on the cassette so I assumed it was manually loaded (they used to buy 36exp rolls wrapped in paper without cassettes back then). When I pulled the film out of the cassette, I discovered almost no emulsion on its surface. Puzzled, I popped the cassette and pulled out the roll from the side. Turns out the emulsion was barely hanging and the friction of the felt of the cassette was enough to scrub it off. My lap and my hands were covered with powder-like substance. To this day I wonder what happened to that roll. I handled plenty of old film, but nothing like this.

 

[halfaman]

Ilford said years ago in some article I read that the expiring date printed on their boxes is based on the pesimistic asssumption that the customer is not going to follow ANY of the storage recommendations (dark, dry and cool place). If you store it properly, you can add a couple of years to the unexposed film date.

 

[ChrisGalway]

........... Amateur films have lower expectations than pro film, so the makers take into mind that marketing distinction to begin with. ..............

I believe this was one of the urban myths that Joe Manthey mentioned in his posts (see reference above). Those posts are worth reading, they certainly make sense to me.

 

[Prest_400]

"Old" photo.net has certainly some nice contemporary discussions. Ron Mowrey (PE) and Ron Andrews did contribute there quite a bit as well.

A while ago I was searching for this topic, but specially the impact of freeing and refrigeration; I link a quite relevant post by Andrews with useful guidelines. Though again, no specific study pointing at some material. It of course must have done internally and indirect references can be found in these discussions.

Life expectancy for refrigerated film

I have a dozen rolls of colour print and slide film from my pre-digital days which have been taking up fridge space since about 2001. I'd like to mail it to a friend who shoots landscapes with film. Most of the expiry dates are 2004. Is it worth the postage to ship it to her, or would even refrig...

www.photo.net

Ilford said years ago in some article I read that the expiring date printed on their boxes is based on the pesimistic asssumption that the customer is not going to follow ANY of the storage recommendations (dark, dry and cool place). If you store it properly, you can add a couple of years to the unexposed film date.

[Edit] 2 years expiration date seems to be the standard across the industry but I have noted that some products, specifically 35mm Kentmere I have bought, do come with longer dates. B&W seems to be generally much more resilient.
Then of course, high speed films have a shorter time to expiration due to their sensitivity. And perhaps might be good to mention that 120 film might be best adhered to this assumption; given instances of mottling/backing paper imprimpting.

 

[koraks]

I believe this was one of the urban myths that Joe Manthey mentioned in his posts (see reference above).

Yeah, I think so, too. There were many myths surrounding pro film, including that it would be pre-aged so as to be on a sort of stable performance plateau during its anticipated service life. In reality, it seems that the "pro" films were/are just the films that incorporate the bees knees of emulsion technology, which gives them comparatively fine grain given their speed etc. - and possibly tighter QA bandwidth. Like you said, it's wortwhile going through Manthey's posts, as well as those by Ron Andrews as mentioned by @Prest_400. Although Andrews posted a lot over the years and it takes more effort to get to the 'good bits' - also, his perspective is more from a manufacturing point of view, while Manthey's was an R&D/engineering point of view, which tends to be more relevant for the kind of things we like to know about here.

 

[Prest_400]

In reality, it seems that the "pro" films were/are just the films that incorporate the bees knees of emulsion technology, which gives them comparatively fine grain given their speed etc. - and possibly tighter QA bandwidth

Don't have a citation handy, but paraphrasing IIRC PE, the (un)maturation would have been true for some products such as Kodachrome (edited for clarity: Historically and not for current pro films). Again, IIRC the point is that Kodachrome shifted towards magenta with age, so it was manufactured a bit "green" in one of the consumer distribution levels.
Though now that I write it, it's mostly jsut that pro films were/are manufactured to spec, and consumer ones had some leeway accounting for the use conditions.

To not edit again, I paste a relevant quote from R.Andrews in that linked thread regarding more specific products.

All films are sensitive to background radiation ROUGHLY in proportion to film speed. That is, an 800 speed film would be roughly 32 times as sensitive as a 25 speed film. This is very rough since the current Kodak 800 speed film is about 1/4 as sensitive as the generation from 8 years ago.

No references, but that post dates from 2008 and at the time they should have had Portra 800-3 and Kodak Max/Ultramax 800; the 8 years ago places the timeline in 2000 and would have been the earlier generation(s) of such 800 product.

 

[ChrisGalway]

........... Again, IIRC the point is that the film shifted towards magenta with age, so it was manufactured a bit "green" in one of the consumer distribution levels.
............

According to Joe Manthey, this might have applied to Kodachrome but is not the case for (then-) current films. https://www.photo.net/forums/topic/...the-expiration-date-for-film/#comment-2215812

 

[Mr Bill]

I have a ton of unique experience with a handful of Kodak pro portrait from roughly 1980 on. These include VPSII, VPSIII, Portra 160NC and plain Portra 160. When I say a ton of experience I'm from an outfit that had literally thousands of company-owned portrait studios in the US and Canada. They all shot whichever of these films were current at the time... all of it shipped from our corporate headquarters. The studios then returned their exposed film to either our main lab or one of 3 smaller satellite labs. (When I say a "smaller lab" these each had somewhere around 50 or 60 full time employees.)

Let me first say that I do not know of any "legitimate" published info on storage life/effects on color neg films. Now, it may sound arrogant, but if I (or people in my QC department) did not know of such published info then it probably did not exist (I should probably say for slower speed pro neg films in the US).

Back to some things I "know" about the named films, from actual experience. When Kodak coated these films entire emulsion runs were reserved for our use. Now we had gotten a bit anal about testing some of these things; I don't recall exactly why, but it was a result of some problem we had encountered. And we didn't wanna get caught again. So... every time a new film emulsion came in our warehouse would semi-randomly pull a couple of 100-ft rolls for us to check.

We had a couple of sensitometers in our QC lab, and we would expose a handful of "step wedges" on each roll, then process film along with a control strip. (This gives a very well controlled exposure test of the film, and confirmed good processing. The results are read with color densitometers and plotted on a chart.) So... we now have a sensitometric record of every film emulsion we use, verified by two identical rolls, WHEN THE FILM WAS NEW.

The next pertinent test... with all of those studios in operation it was a routine thing for a new studio manager to come across a half-dozen or so rolls (100 ft) of film stuck away somewhere. Since the condition of these rolls was unknown the studios would return them to the home office for testing. We would open the cans in the dark to check for "proper spooling" and then expose several sensi wedges. Again, processed alongside a control strip. So... we now have samples of known-emulsion # film after some period of time in field locations.

Here's some general results, which made me realize how wrong a lot of magazine writers and professional photographers were about certain aspects. I sorta grew up hearing that for critical jobs the photographer should buy all of their film at the same time, and the same emulsion. Our findings: first, most of the new emulsions were virtually identical. (If sensi wedges in well-controlled processing cannot detect a difference then there is no way a photographer could.) Now, there were a small number of emulsions with a slight difference - a sort of signature, if you will; too small for a photographer to detect during shooting. But WE could detect it.

Here's the second thing, which WAS surprising to us/me: however an emulsion looked when new, it continued to look identical as it aged. The photographic "press," various "experts," would often describe how color films change as they age, so you should use them at their "sweet spot." Our testing showed that this was a bunch of baloney, at least for the specific pro color films I named above. We were getting something like a couple dozen returned rolls per week which is roughly a thousand per year, every year, so a pretty decent sample size. For some emulsions we would returned samples as much as 2 or 3 years PAST the expiration date; same result - they were sensitometrically IDENTICAL to the same emulsion when new. Fwiw this is just a point of curiosity; the studios just did not want to shoot on outdated film so we just used it for internal testing or even discarded it (although it was perfectly usable). I should say that I would not arbitrarily extend these observations to higher speed films as different mechanisms might come into play.

Third thing... we did very occasionally get some studio film, with actual portraits, that had a certain sort of fog. (They printed ok, but the film difference was visually obvious.) Now, we sorta figured it was probably a result of storage at too-high temperature. We DID have a small traveling operation, perhaps two or three dozen photographers, carrying equipment sets in their car, for shooting in towns too small for a full-time studio. A number of these were based in the desert southwest of the US, climate similar, for example, to Las Vegas or Phoenix, Arizona. We figure that maybe a photographer leaves the film in their hot car sometimes.

So... we figure...let's do some high temperature film storage over a period of time to see how long it takes to damage the so-called delicate professional portrait films. First I stuck some temp probes in a car, hot day for us, maybe 95 degrees F, black asphalt parking lot. It gets nowhere near as hot as I was lead to believe (at least where the film would be). So an actual car isn't gonna get as hot as we want. We decided to rig up a "hot box" to hold a controlled temperature. We picked 140 degrees F as a worst-case scenario. (This ought to damage the film pretty quickly, right?) We plan to pull a first sample after maybe 2 hours,a then 4 hours, then a full day, etc. Just keep doubling time intervals until the film is unusable. This testing was done on Kodak VPSIII as I recall, the immediate predecessor of Portra 160NC. As usual we'll use full sensitometric wedges, tri-color plots. We decided to test both 35mm and 70mm film since we used both. And to make it more interesting we threw in a couple of amateur films to see how rugged they were. (I don't remember any more, but I'm thinking Gold 100 was one of them).

The test procedure was, roughly, put all the individual unexposed films in the hot box. At predetermined intervals take them out, give some time to cool down, then expose sensitometric wedges. (Since we know how to test various things we also hold the exposed film long enough for latent-image-shift to stabilize, based on prior tests.) At that point the test films are all processed along with a control strip. Then take tri-color density readings and plot the curves.

Results: my memory is getting fuzzy on exact results, but if you search my posts here for "hot box" I think I may have posted more details. The heat is on 24 hours a day so we just use total hours. But keep in mind that a hot car is only real hot when in the sun, so less than a half day. Anyway, we keep increasing time intervals: 1 full day, no film shows ANY change on the sensi wedges. I think we decided to pull film samples at 50 hour intervals. By 100 hours = no changes. By 200 hours, no changes. Somewhere around 300 hours ALL of the amateur films are beginning to show a change; pro films = no change. Finally, roughly 50 hours after the amateur films begin to change, the pro films begin to change (the 35mm vs 70mm films behaved very slightly different).

Conclusion: 350 hours in our hot box is roughly 2 weeks. But in the real world this sort of temperature could only be maintained at most half the time (less than 12 hours direct sun per day). So this would be in excess of double the days, or over a month in a hot car. We figure that none of our traveling photographers are ever gonna accidentally leave film in their car for a month so there is no point in testing this any further.

As a note the occasional "fogged" portrait film doesn't look anything like the heat damage. Eventually the cause was found, but it didn't have anything to do with either us or the film's ability to handle heat.

 

[bernard_L]

Kudos for debunking yet another urban legend.

The photographic "press," various "experts," would often describe how color films change as they age, so you should use them at their "sweet spot." Our testing showed that this was a bunch of baloney

 

[DREW WILEY]

Nothing I have read so far on this thread has changed my mind in the least; nor have I learned anything new from it.

Professional films once came with recommended filter corrections per batch, and based upon the expectation the film would be properly stored prior to use, and then used within a reasonable period of time. Now batch to batch quality control is much better. But color films DO shift color balance with age, and if too old, end up with serious
crossover issues. I've encountered that MANY times, and with color papers too.

Not film per se, but I did time Cibachrome batches for their "sweet spot" in the aging process, and it made a giant difference in the quality of the results. But that was a photosensitive medium which shifted quite rapidly once out of cold storage, within six months in fact, and generally from a green bias to a magenta one. So I'd pick the appropriate images for the correct points in the overall color shift cycle. You couldn't just rebalance everything with colorhead settings. It was like aging steaks for the best flavor.

In terms of film, I have received allegedly brand new boxes of both Fuji and Kodak dupe sheet film which was worthless right from the start due to hopeless highlight crossover. These kinds of slower selling products are particularly susceptible. I've gotten bad lots of Fuji Astia due it selling more slowly than their other chrome films.
Those are, of necessity, very acutely balanced products. But with typical color neg film, it's harder to detect hue shifts because so much latitude has been built into a particular category of color related to skintone reproduction, generally at the expense of other categories. You also have less contrast to begin with.

So this is not an "urban myth" at all, at least in principle. The whole point is not to allow your materials to get outside the safe zone of usage, which can vary between different specific films and real world conditions. Those of us who sometimes bought outdated film knew what to expect - use it up more quickly than fresh film, because it would shift a lot faster than fresh film, even when initial tests seemed fine. And incidentally, I primarily shot 8X10 color film for a couple decades, which is now running around $40 PER SHOT with processing included. Just how much gambling is one willing to risk?

In recent decades, there has been a push to make pro color neg films more resistant to aging or travel related heat changes, but it's still a factor if one is careless. By now, everyone should know not to leave film or a loaded camera in a hot car trunk, not even for an hour. In this day and age, in some summer climates, it can easily get 150 deg F in there, 170F in some desert places. There are frequent circumstances in our American Southwest where people are dying if their auto air conditioner fails. Film isn't immune to climate change either.

And everyone should know not to have unsealed film in a damp humid area either. For gosh sakes, if it's bad for the camera, it can't be suitable for the film either. I had to get nitpicky about which dealers I bought my color film from,
depending on their storage habits and inventory rotation basis, whether consistent or not. One can't take for granted that a middleman has done the right thing. If some corner of the camera store smells musty with mildew, it can't be good for the products.

 

[MattKing]

The "Pro" designation at one time did indicate a difference.
But it was more that the non-pro films were designed with uncertain storage and use conditions in mind.
Those were the days when some pro films came with batch specific filtration suggestions, and when the distribution channels helped ensure climate controls.
All of that morphed into something different though. Batch consistency improved - no filtration recommendations required any more - pro film became a bit more robust, and eventually the "Pro" designation came to exclusively designate the distribution and marketing channels, rather than any special attributes of the film. That is why all black and white films came to be designated as "Pro".

 

[ChrisGalway]

Thanks to everyone for their input.

There appears to be no rigorous published study of the degradation of colour film with time.

But based on your input and past posts in photo.net, especially the input of those of you with connections to Kodak and/or extensive experience as a professional, my take-way is that for slower films (Portra 160 and slower), it's unlikely you will notice much degradation, if any, for well-stored films within a couple of years of the date written on the film carton. And perhaps longer, 4-5 years depending on your level of critical assessment.

Would anyone disagree with this?

In the past, I usually used all film by the printed date, but at the moment ... due to panic buying ... I won't use all the film stocked up in my freezer by the printed date. One of the problems now is that you have to buy film as it becomes available (especially colour transparency film), leading to my over-stocking issue!

 

[koraks]

Would anyone disagree with this?

Not really; the only caveat I would make is that I've seen some 'special effects' of backing paper interactions on particular Kodak Portra 160 & 400 films that were stored refrigerated and left to expire. Expiration was a little more than the 4-5 years you mention; more like double that IIRC, but not more than about 10. Color-wise everything looked OK(-ish), but the first section of the roll would have faint imprint from the backing paper.

 

[MattKing]

I agree with koraks - the issue is different when considering film with backing paper vs. film without backing paper.

 

[DREW WILEY]

I've often shot sheet film 20 years out of date with no problem, both color and black and white. It was kept frozen the whole time prior to usage. I recently sold off all my 8X10 Tech Pan, which was coated over 40 years ago. I tested it first, and it was still normal with no fogging; but that's a variety of film which is exceptionally stable.

I'm more conservative stockpiling 120 film due to the alleged backing paper problem. But all my older stock prior to that issue did fine; and now my new inventory of TMax 120 and Ektar is probably safe. I never have had a bad roll. But I don't buy more than a year's worth of 120 film at a time.

 

[reddesert]

There appears to be no rigorous published study of the degradation of colour film with time.

I just want to add that, it's clear from context that this post and thread are talking about the degradation of unprocessed (and probably unexposed) color film. For any future reader, it's worth qualifying that there is a lot of published research on the degradation of processed color film, slides, prints over time, since photographers and archivists have been concerned about that issue. For example, look at Henry Wilhelm's book, which was one of the standards on the subject in the film era, and which he has generously made available as a free download: http://www.wilhelm-research.com/book_toc.html

 

[ChrisGalway]

I just want to add that, it's clear from context that this post and thread are talking about the degradation of unprocessed (and probably unexposed) color film. For any future reader, it's worth qualifying that there is a lot of published research on the degradation of processed color film, slides, prints over time, since photographers and archivists have been concerned about that issue. For example, look at Henry Wilhelm's book, which was one of the standards on the subject in the film era, and which he has generously made available as a free download: http://www.wilhelm-research.com/book_toc.html

Yes, I was asking about unexposed and unprocessed film.

Wow, what a book! Thanks for drawing our attention to it! I think Wilhelm must have been a pioneer of "open access" publication which is now the norm in scientific research (as opposed to closed access behind expensive paywalls).

 

[Mr Bill]

Wow, what a book! Thanks for drawing our attention to it! I think Wilhelm must have been a pioneer of "open access" publication which is now the norm in scientific research (as opposed to closed access behind expensive paywalls).

Yes, but I think his main concern was when he first became aware of the poor image stability of many color images - I'm thinking roughly 1970ish (I'm sure the book will clarify this). He was especially concerned that the manufacturers, in general, had not been forthcoming to the general public with respect to the limited life of such materials.

In the later 1970s, when I became a QC guy (large lab) 3M had been developing a color paper in a sort of partnership with my employer. At that time we knew about the big variability between different papers, and had a lot of concern. We had a 100% satisfaction guarantee on our portrait products, so... Our 3M rep put me in touch with one of their guys, a top notch guy overall who's business card simply said "Division Scientist." He was on the ANSI image stability group, and told me that I needed to be in touch with another guy on their committee who he described as "the Ralph Nader of image stability." (Does anybody even know about him anymore?)

Of course that guy turned out to be Henry Wilhelm, and he was extraordinarily generous with his time and advice, and his concerns (ie, the potential loss of photographic records of famiies as well as motion pictures and historical records). Consequently we set up our own image-stability testing program per his recommendations. (Actually we had been using a home-built" "Fadeometer" which I think was built per ANSI standard specs.)

The dye fading of color materials has essentially two main modes - one is fading due to light, the other is just an inherent dye loss over a long period of time. For useful tests they need to accelerate the dye fading (it doesn't help to wait 50 years to find out if a projected lifetime of 50 years is accurate). So for light-fading one basically uses a brighter (but not TOO bright) light. And for dark-fading, a higher temperature at controlled humidity levels works. BUT, to PREDICT a lifespan (to a predefined loss of dye) one wants to have a handful of different temperatures. It's a bit elaborate but if one finds the time to reach a given dye fade at each of the temperatures, and plots them on graph of absolute temperature vs log of time, the plotted line can be extended to the desired storage temperature (typically room temperature). Then the predicted time can be read off the graph. It's called the "Arrhenius" [spelling?] method after the chemist who discovered the relationship. (There is no similar "predictive" lifespan test for light-fading, as far as I know.)

In our case we only got a single environmental test chamber (they were about $10,000 US at the time, for something about the size of a small "personal" refrigerator). So we could not do "predictive time-to-fade" tests, but rather only comparative tests between different materials. Similar to how we did light-fade testing. We used, as an aim reference, the professional Kodak paper of those days. Not too much later than this Konica introduced, to the US, a new professional color paper called "Century Paper," as I recall, or SR-100 paper (I'm thinking). The big selling point was 100-year lifespan of dyes (to a given % of dye loss) in room-temp dark storage. This was the beginning of a new era improved lifespans for color photo papers.

 

[koraks]

one is fading due to light, the other is just an inherent dye loss over a long period of time

Note that the latter is not necessarily or exclusively 'inherent'. It's influenced by factors like temperature and humidity, but also free radicals (e.g. ozone). This is something that Wilhelm's tests doesn't account for and AFAIK it has gotten him into some deep discussions with a.o. Fuji, who of course do their own tests based on their own understanding of the material and deterioration factors involved. I know that in one of the conversations with Fuji engineers I mentioned Wilhelm and they all started sort laughing, saying things like - "oh yeah, the notorious Wilhelm, we know him alright". IDK what the nature of the dispute was, only that I could surmise from their response that there had been some in-depth discussions between Wilhelm and Fuji people. I suppose they all have their own views on what the factors are that influence longevity and in particular what a good methodology for testing this would be.

This is not to discount the value of Wilhlem's work - far from it. Especially in a landscape where much of the testing is done behind closed doors and we never get to see any concrete results (only marketing pitches exploiting advantageous outcomes), it's super valuable that something more substantial is made available to the general public. I would caution against taking Wilhelm for gospel (which I don't think he ever intended that way, to begin with). There are more varied views on the matter and the outcomes/conclusions may very well deviate substantially on methodological and conceptual grounds.

 

[Mr Bill]

Note that the latter is not necessarily or exclusively 'inherent'. It's influenced by factors like temperature and humidity, but also free radicals (e.g. ozone). This is something that Wilhelm's tests doesn't account for and AFAIK it has gotten him into some deep discussions with a.o. F uji...

Yeah, well inherent might not be the proper word, but my thinking is that the chromogenic dyes (a dye coupler combined with an oxidized developer molecule) simply are not extremely stable. And in "normal" temperatures, by which I mean the range where humans can live, I think a certain proportion of those dyes are gonna degrade over some period of time, in the dark. And these are the sorts of things that will show up in an "Arrhenius test."

FWIW we ran our "comparative tests" on a wide range of color papers for probably over 20 years, on probably about every pro portrait-style paper from Kodak, Konica, and Fuji in that time frame. (As a large buyer, about a dozen master rolls every day, we were a sought after customer, so every new product available in the US, the tech/sales reps wanted us to see it.) And I don't recall ever hearing about a paper where there was not a reduction of dyes via densitometer measurements in our tests. (Even after I was out of QC the people doing the tests would, I'm sure, have told me about such a thing; the serious photo nuts all share such things.)

One note about how well the Arrhenius test might predict... our own single point temperature/RH could not make predictions. But we could generally get various info from the manufacturers (corporate secrecy agreements which were never broken, but as far as I know, allowed this). Anyway at one time Kodak had a CIS document giving Arrhenius test predictions on some of their films. (As I recall Wilhelm did publish this CIS, or at least part of it in his book.) It included our mainstream film of that time. Well, I happened to have some pertinent film samples filed away. My department used to shoot our in-house printer setup negatives in those days - something like 6 or 8 hundred sets every year. So I had a couple sets, including all the density data, etc., filed away. So just for fun I pulled out the negs and reread on a densitometer. Then compared vs what the CIS document had predicted. I kept this stuff in a file folder and periodically checked ever several years until the film was over 30 years old (stored at office temperature and humidity, around 72 degrees F and 50% RH). The tri-color densities tracked right down the middle of Kodak's predicted range. So my personal experience in this one case supported the accuracy of the Arrhenius method.

Regarding ozone, are you sure that Wilhelm did NOT test for this? I haven't really followed his testing for probably 15 or 20 years, but I know for sure that he was aware of the problems. I recall at one time an affordable inkjet printer had come on the market and his published test results gave it pretty good longevity results. But... the real world experience had a lot of cases where the images went bad in a very short time frame. And it turned out to be issues with ozone in certain places - certain equipment (maybe copy machines?) produced enough ozone to be a problem. So this hurt his reputation in the press. So I'm sure he did further research into the ozone situation; I'm just not sure how this comes into later publications. FWIW I think this was also a major failure on the part of the printer/media manufacturer.

In later years I've also looked at a number of inkjet and dyesub printers for use in our studios. One inkjet media maker, I believe it was Ferrania, used a paper with some sort of catalyst to deal with ozone. They told me that another maker, very well known, used some sort of sacrificial material to deal with ozone. The thinking was that for ozone testing the sacrificial material would eventually be used up, but have good test results until that point. Whereas with the built-in catalyst moderate ozone should never be a problem. I dunno cuz we never specifically tested for this.

 

[Mr Bill]

I know that in one of the conversations with Fuji engineers I mentioned Wilhelm and they all started sort laughing, saying things like - "oh yeah, the notorious Wilhelm, we know him alright".

I know there was a certain animosity toward Wilhelm by a number of Kodak people. (I think even PE, on this website expressed the same thing.) I don't know exactly why, but I suspect it was largely that he was a potential threat to their livelihood. He wanted image stability info to be public. But if the manufacturers let this out as a competitive issue, we'll, what's gonna happen to the company with the poorest stability? Who's gonna buy their product unless it's at a substantial discount? So at least in those days Wilhelm could possibly be seen as a guy who could potentially push the paper manufacturers into an image stability "arms race" against each other. So they don't wanna go there.

FWIW on the occasions where someone has disparaged Wilhelm's methods and I looked into the details, I've always found Wilhelm to be vindicated.