Everything Scientists Know about Making Negatives Last Generations

10 min read

Most people believe that film is an archival medium when compared with digital files. The fact that we still have so many images from the late 1800s, when photography was just starting to reach the general public, is a testament for how long film can last. 

But the fact of the matter is, film negatives are permanent if they aren’t stored properly. In this article, I’m going to go over the peer-reviewed research that shows approximately how long film will last, and what you can do to ensure these negatives make it to the next generation. So how long can a roll of film last? 

The average roll of 35mm or medium format film will start breaking down within 40 years if stored in a dark place at room temperature with a 50% relative humidity. But it is possible to keep film negatives lasting for more than 200 years if they are stored properly.

The relative humidity is the biggest predictor of how fast a negative will break down. High humidity environments mean there will be more water around the negatives, providing the perfect environment for the film base to decompose, the dyes to fade, or for the film to react with volatile organic compounds in the atmosphere.

Even though negatives feel fragile, there are a number of steps you can do today that’ll increase their lifespan significantly. This article is going to go over a number of factors that can help increase the lifespan and archivability of film stored at home — because not all of us have the means to purchase a storage unit capable of maintaining 40°F/4°C and 20% relative humidity to store the pictures of our cats in for the next 800+ years. 

What causes film to break down?

Film is greatly affected by the environment it’s stored in. If it’s stored too hot, the emulsion will become a gooey, sticky mess. Too cold and dry, the acetate backing on the negative can become brittle and breakable. But if it is too humid, then mold and fungus will find the gelatin becomes a wonderful home, just like it can inside of your camera.

But negatives are also affected by what they’re stored in. When negatives degrade, they release acetic acid, which makes them smell vinegary. If this acid isn’t ventilated, it can cause a chain reaction causing other negatives to begin to break down. So over time, it’s important to keep negatives in a porous box, like those made from paper or cardboard, as tin or other metal boxes will keep the acidic fumes inside. 

Film can also degrade when it’s stored near volatile household chemicals, like those found in glass cleaners, furniture and wood polish, mold and mildew cleaners, turpentine, or hydrogen peroxide. As a general rule, it’s safest to keep film stored far away from the cleaning cupboard. 

But likely the most common issue that film photographers will face is fixer contamination. If there are even small amounts of fixer left on the film, it can cause film to degrade faster than expected. The best way to ensure you don’t transfer fixer to your film after washing is to wear gloves during development. Take the gloves off when you’re finished washing the film to eliminate the risk of transferring the residual fixer back onto the negatives. 

How do I know if film negatives are starting to go bad? And what happens when they do?

The most common sign that film negatives are starting to deteriorate is that they will produce a vinegary smell. If you open your film storage and smell that pungent odor, immediately find the affected negatives and transfer them to a new location. 

According to The Image Permanence Institute (the organization that created the first standardized tests for film decomposition), vinegar, being a weak acid, won’t immediately degrade the film. The first signs, however, are that the color dyes will begin to fade, and the emulsion will become softer. 

As the decomposition progresses, the gelatin emulsion can start to stick to the plastic negative preservers, while the acetate base will start shrinking and become extremely brittle. When the acetate base shrinks, it lets go of the emulsion in certain places, forming channels in the negatives. The negatives can also form crystalline, or liquid-filled bubbles underneath the emulsion. 

However, there is no accurate way to determine how long this decomposition process takes. The speed is unfortunately dependent on so many individual factors, that it’s impossible to give one simple answer. 

How should film negatives be stored for maximum longevity?

Film won’t start degrading for up to 800 years if it’s stored in archival sleeves at 40°F/4°C at a relative humidity of 20%. But since none of us are capable of doing that at home. So what’s the best way that we can keep negatives lasting as long as possible? 

The best way to keep film negatives lasting as long as possible is to keep them stored in archival sleeves in a cool, dry place. They should be stored in a porous container that allows some ventilation, and with some distance from other negatives if possible. 

According to the Image Permanence Institute study, film degrades at a much slower pace if there is some way for the gasses to escape the enclosure. Unfortunately, it’s not always possible or practical to keep the negatives in separate containers. But some spreading can at least lessen the effects of one negative spoiling the bunch.

Which films are the most archival?

There are two types of film base that are commonly available. Triacetate and polyester. Triacetate films are the most common, making up the vast majority of film still produced today. Unfortunately, triacetate doesn’t last as long as polyester bases, which are known to last 5-10x longer than acetate-base films in the same storage conditions.  

Ilford, Kodak, and Fuji all exclusively use acetate film bases on their remaining commercially available film stocks. These films are not as archival and are expected to last 50 years at 50% humidity, and standard room temperature. Kodak used to produce Technical Pan film, which was designed on their patented Estar polyester film base.

Agfa, Rollei, Bergger Pancro, and Japan Camera Hunter all use polyester film bases. Rollei’s films on their polyester base come with a tested life expectancy of 500 years! 

So, if you’re doing a project that you’d like to have around for some time, the films most likely to outlast you will be the black and white films on the polyester bases. Color film dyes will still break down over time no matter what base they are coated onto, however.  

Polyester bases are so strong, they can break the camera before they tear.

How do I tell if a film is made from polyester or acetate? 

There are a few ways to tell the difference between polyester and acetate film negatives. 

In most cases, acetate films will have a translucent purplish-grey appearance, while polyester films will appear perfectly clear. If the film is stained using a pyro-type developer, however, this may not be as apparent. 

The next way is to look for the Kodak Estar numbering on the film. Films like Japan Camera Hunter Streetpan 400 have the number 1701 on the side of the film, which is used by Kodak to denote the Estar base. Polyester films will also exhibit a stronger curl than acetate films, which are far easier to straighten.

If you can’t tell from those last two tests, there is one more option, although it is destructive. Acetate film tears easily, while polyester bases cannot be torn. This is actually one of the main reasons why some manufacturers keep using acetate. There were cases on movie sets where the polyester bases resisted tearing so much that if the film jammed while moving at high speeds, it was more likely to break the camera than the film. 

In the end, it’s much cheaper for Hollywood to replace a roll of film than an entire camera. 

Are sepia, selenium, and gold toners archival? 

One of the biggest myths that is actually still believed by many is that film toners make negatives more archival. Selenium was a favorite archival toner used since the turn of the century, although many have also touted sepia and extravagantly expensive gold toners for the same effect. 

However, when the Image Permanence Institute tested these toners back in the late 80s, they quickly found that the toners do have a partial archival effect, but are overall unreliable. 

“[Gold] and selenium treatments provide protection against peroxide attack only in proportion to the degree to which the heavy metal is substituted for the original silver image. In the absence of sulfiding agents, even very high degrees of gold or selenium substitution do not provide complete protection. In actual practice, when used as recommended, the metal components of gold and selenium toners for microfilm do very little to protect against oxidation; their effectiveness is almost entirely due to the sulfiding action of other constituents of the toner formulas.” – James M. Reilly said during a 1988 presentation of his team’s paper Stability of Black-and-White Photographic Images, with Special Reference to Microfilm.

The paper found that there was another actor that was imparting the partial protective properties. Upon further investigation, Reilly’s team found that polysulfiding agents were enhancing the film’s archival properties. Polysulfiding agents are found in low quantities in selenium and gold toners, but not enough to provide complete protection. 

What solutions do lengthen a film negative’s lifespan?

At that time Kodak had been producing Kodak Brown Toner, which contained polysulfiding agents. Reilly’s team at the Image Permanence Institute found the solution to be a good archival solution, even at high dilutions such as 1:200. 

But since then, Kodak Brown Toner has been discontinued, according to Freestyle and B&H.

According to The Film Developing Cookbook by Bill Troop and Steve Anchell, there is another formula that can be made at home. Their book is an essential guide for anyone getting deeper into film photography and has inspired many articles on this blog. Check out their book on Amazon here (this affiliate link helps support my blog without raising the cost for your. Learn more about our affiliate policy here). gives the formula developed by the Image Permanence Institute that gives the maximum archival stability to B&W negatives. Here’s the formula: 

Step 1. Mix 495g sulfurated potash with 1L of de-ionized water, and seal the bottle
Step 2. Add 20g/L sodium tetraborate decahydrate, and ensure solution pH of 13
Step 3. Dilute concentrate no more than 1:25 in demineralized water. 
Step 4. Use the solution and a final rinse in two separate, dedicated tanks to avoid contamination

While this solution seems simple enough, Troop and Anchell note that it should be carried out by a professional chemist underneath a fume hood, as the solution may produce hydrogen sulfide gas. If that’s not possible for you, then the next best solution is to seek out polyester film stocks, like those made by Rollei, Agfa, Japan Camera Hunter, And Bergger.

Was this article helpful? Or do you have any more questions about image permanence? If so, let me know down in the comments below, or join the growing Official Learn Film Photography Facebook group

By Daren

Daren is a journalist and wedding photographer based in Vancouver, B.C. He’s been taking personal and professional photos on film since 2017 and began developing and printing his own photos after wanting more control than what local labs could offer. Discover his newest publications at Soft Grain Books, or check out the print shop.

2 thoughts on “Everything Scientists Know about Making Negatives Last Generations”

  1. I have 100 year old glass plate negatives my Grandfather made.
    They still print wonderfully.

    • That’s amazing! Those images must be so cool to go and look back at. I’d love to one day learn how to shoot glass plates. It makes sense that they’d last so long, considering there’s no acetate to break down. So long as the plates were developed and fixed properly, there shouldn’t be anything that can ruin them — other than being dropped, of course.


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