A stinker of a problem – Film and vinegar syndrome

Do you hold photographic records dating from around 1910 – 1990’s?  If you do, then there’s a good chance that your negatives, slides or transparency film is suffering from a condition commonly called ‘Vinegar Syndrome’.  And if it is, then you will probably smell it before you see it!

So, what is Vinegar Syndrome?

It’s a decomposition reaction that occurs in cellulose acetate plastic film and once it starts it can’t be reversed…well not yet, but researchers are working on it!

Ironically, acetate film (called ‘Safety Film’) replaced the dominant plastic at the time, cellulose nitrate, which is even more sinister and nasty. 

Nitrate film has a reputation for self-combusting, producing intensely fierce infernos nigh on impossible to extinguish.  In its day nitrate film caused horrific fires and is still a problem for archives to deal with safely today, but that’s another story.

Acetate film won’t blow up in your face, but its long-term prognosis isn’t good either.  This is where vinegar syndrome comes in.

As the plastic degrades it produces acetic acid, giving off a characteristic vinegar smell.  It goes through other stages including the ‘butyric stage’ producing a plethora of odours some liken to rotten butter, spoiled milk and even baby chuck – nooice!

What does vinegar syndrome look like

You may see little sweat pimple bubbles, blisters and channelling, right the way through to full separation of the plastic film carrier from the image/emulsion layer and white crystals.

Depending on what else may be going on the film may sweat or feel wet, oozy and sticky. 

The film distorts, shrinks, buckles, becomes very brittle and may crack and flake on handling. The image is virtually impossible to see or digitise.

Here’s an example of one affected negative and the typical damage. The first picture is the film side (front) and the second the emulsion side (back) of the negative. You can see some of the characteristics we’ve talked about such as channelling, separation, blisters, bubbles, distortion, shrinkage, cracking etc. 

The last example picture is how the image on the film looks through transmitted light … not great!

Image of film affected by vinegar syndrome – Film side
Image of film affected by vinegar syndrome – Emulsion side
Image of film affected by vinegar syndrome showing how the image looks through transmitted light.

How do you slow down vinegar syndrome?

Like all chemical reactions, it’s worse in warm to hot and humid conditions – Yep, you got it – typical for Queensland.  And once the reaction reaches the auto-catalytic stage, the horse has literally bolted. 

If you have a mix of some film with vinegar syndrome, some without, and some really advanced, well the affected film can initiate reactions in its otherwise clean and ‘healthy’ neighbours. 

That’s why it’s a good idea to separate and isolate ‘infected’ film.  Materials like paper close by will soak up the vapours as they off-gas.

You might also need to bag it for health and safety reasons (although for most people the gag reflex kicks in before concentrations reach harmful or lethal levels). Even chronic low-level exposure may need assessment by your health and safety expert.

There’s not much else you can do but keep it cool and dry. 

The jury is still out on whether affected films can be recovered.  Frustratingly, the image/emulsion layer is unaffected chemically by this reaction.  We just need to work out a viable and cheap way to remove and replace the stinky degraded acetate with something more archival.

The good news is that from around the 1990’s polyester became the preferred film for photographic stock and…touch wood…has proven pretty stable over time and you won’t see this problem in contemporary photographic records.

And then there is digital photos… but that’s a whole different preservation story.

More information

You can find information and advice on the best environmental conditions to store your film and other audio-visual material on our website.

And if you need to deal with photographic records you suspect may be affected, give us call on 07 3037 6777 or send us an email to get some specific advice.

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