Does your photographic film or microfilm storage area have a faint smell of vinegar? Is it acrid enough to make your eyes water, or affect your breathing? Are you and your staff afraid to enter the room because they instinctively know something is not right?
If the answer is yes to any of the above, your microfilms and negatives are probably suffering from “Vinegar Syndrome”.
This resource provides insight on how to detect acetate film base degradation, successfully manage a film collection, and prevent Vinegar Syndrome from destroying a collection.
About film substrates
Photographic materials have been produced with a variety of chemicals and substrates since their advent. In the early years from 1890 through 1930s nitrate (or nitrocellulose) base was used for cinematographic, photographic and microfilm substrates and we probably all heard stories of them being prone to spontaneous combustion. In the 1930s and certainly from the 1950s in New Zealand most of the above film substrates were manufactured using a cellulose acetate base, which with homage to its predecessor was often known as “Safety Film”. Scientific tests spearheaded by Kodak suggested this film would have a life expectancy of up to 100 years if stored correctly, and in truth this was accurate.
Acetate film was used in New Zealand as late as the mid 1990’s by some organisations (NZMS spearheaded the shift to polyester from June 1990). Polyester is a particularly rugged plastic base, extremely stable, offering a life expectancy of 500+ years when properly processed and stored.
What is Vinegar Syndrome?
What does it smell like?
You can normally smell Vinegar Syndrome before you can see it. The side effect of the film substrate breaking down is the production of acetic acid (vinegar); the biggest sign of a deteriorating acetate collection is the smell of vinegar!
“Chemical reactions influenced by heat, moisture, and/or the presence of acidic vapors from nearby degrading film cause acid to be generated within the cellulous acetate support. From there it diffuses into the gelatin emulsion and often into the air, creating a sharp, acidic odor.” – A-D Strips User Guide.
What does it look like?
Fig 1. A microfilm suffering from extreme degradation.
Here the microfilm is extremely buckled and twisted, the emulsion has dried out and is shedding off in parts, the layers of the film on the roll have actually fused together and the emulsion has crystallised on the inner layers of the film and are getting steadily worse. Less than 10% of the intellectual content (in the images) on this film was recoverable.
Fig 2. Examples of the emulsion degradation that occurs in acetate microfilms.
In the image on the right you can see the emulsion has crystallised giving an almost blurry look to the text. Both images exhibit crystallisation which looks a bit like crazed ice over a puddle or lake.
Fig 3. Two images captured from microfilms of the same era.
Of the same vintage, the reels were produced in the same year and probably stored together in the same drawer for decades, one might assume they would be of similar condition. Without a proper assessment, there is no easy way to determine how severe the loss of information may be. The cause of the difference in condition was probably the difference in moisture content of each reel (how they came off the processor), or that one of them was stored close or adjacent to a heat source such as a computer, or radiator, or heat from the sun through the window.
Fig 4. Photographic collections can also suffer from the same vinegar syndrome.
Here, the image exhibits buckling and the lines on the image are the early signs of cracks in the emulsion which will steadily get worse and ultimately render the image illegible. Urgent action in the form of duplication or digitisation had to be undertaken promptly to save this image.
To ensure the longevity of your photographic or microfilm collection, films are best stored in a stable environment as cold and dry as possible. Ideally, the temperature should not exceed 21°C and relative humidity should be less than 50%.
They are better housed individually in acid free paper, card sleeves or boxes and stored in open or breathable containers.
It is critical to isolate any items that present symptoms of Vinegar Syndrome from the rest of the collection as soon as they are identified. If left with the collection the fumes from the degradation process will hasten the deterioration of other acetate films around them.
Chilling will help to slow the degradation while they await further assessment and digitisation, although you must think carefully about the introduction of moisture which can accelerate the degradation. At this stage you should develop a conservation and management plan for your collection which will include ongoing assessment, and a plan for duplicating onto the more stable modern polyester films as soon as practical, digitising them or a combination of both.
It is so important to detect the degradation of your acetate collections early so that remedial action can occur. The first step is to assess the acetate film in your collection and you don’t want to rely on sensing vinegar smell to determine that as by then it may be too late to recover your data.
Film can have acetate, nitrate or polyester substrates. There is very little, if any, nitrate microfilm in New Zealand collections, as nitrate was most commonly used in the movie industry and for all intents and purposes acetate from polyester substrates look identical.
The production date of the film or microfilm renders a good clue as to the substrate but there are some physical tests using an invasive technique such as tearing, or a less invasive technique such as light channelling, to identify acetate from polyester.
NZMS staff are trained in a range of techniques to identify which substrate is present in your collection.
Fig 5. Inspecting microfilm collections suffering from vinegar syndrome.
As mentioned, your nose also provides a terrific detection system, although at this stage your collection is in trouble. Films in the early stages of Vinegar Syndrome are easy to detect due to the recognisable smell produced. This is often known as the trigger point or auto-catalytic point where the degradation/decomposition accelerates exponentially. Assessment is critical at this time if it hasn’t been done already. Adjustments may have to be made to both the storage environment and access. Temperature and relative humidity should meet current recommendations and acidity monitored with A-D Strips.
More visible signs are that the film can buckle and twist; the film structure starts to warp. In these situations, it becomes difficult to reformat as the film edge is no longer straight and difficult to duplicate or digitise. The films also become brittle, and the emulsion can start separating from the base and crumbling away. Unless caught early on the accumulation of acetic acid will destroy the images on your films.
Crystallisation can be seen on the film and it will start to fuse to itself together and become difficult if not impossible to handle.
Fig 6. 16mm Microfilm suffering from advanced degradation/vinegar syndrome.
During the assessment, an understanding of the scope of your collection can be built. For example, the number of images on a roll of film can be measured or the number of negatives in a box or sleeve can be counted. Any forms of taxonomy or indexing: collection identification, that you may have recorded digitally or in catalogue form also provide useful guidance. All this information can contribute towards understanding the extent of your ongoing storage costs (enclosures for the material as well as the environmental conditions), preservation, duplication and digitisation costs. These are important factors in developing your collection management plan and ongoing funding costs.
Films that are in the earlier stages can be detected via a more scientific method than one’s olfactory system by using the A-D Strip testing (Acid Detection) system.
Fig 7. Assessment of microfilm reels for vinegar syndrome using A-D Strip testing (Acid Detection) system
The litmus PH paper strips evaluate whether the films are undergoing acetate degradation. A-D strips come with a pencil that has a key indicating the different state of films. This can help to identify which films should be isolated, duplicated, or digitised. The A-D strip scale runs between 0-3, with 0 as stable (Blue) and 3 as undergoing severe degradation (Yellow). In the picture above, you can see different colour test strips reflecting the condition of the films they are sitting with (they were placed in the boxes with the films).
You can purchase A-D testing strips to monitor your acetate film collection and its potential degradation. You can purchase A-D strips from this website.
If your film shows any signs of degradation or Vinegar Syndrome, it is crucial to act fast. We recommend you bring it straight into NZMS for a full assessment. Once appraised we can make recommendations and devise a plan with you for preservation of your data & records through duplication onto modern polyester microfilm or digitisation.
If you have microfilm or photographic negatives in your collection you may or may not have a plan for managing your collection. A plan is important, and should factor storage and access conditions as well as the containers the items are held in. You should have a good understanding of what is contained in the collection but often collections are inherited and only described at the macro level for example “City Photographer’s Studio Photos circa 1958”. At some stage you will want to know what content you want to keep and perhaps digitise, and what you may discard. Most importantly from a longevity perspective you need to know whether they are polyester, acetate or nitrate, NZMS can help you with this.
It’s timely to cite Paul Negus from GenusIT (UK):
“People say microfilm is old fashioned and therefore we should replace it. Paper is over 2000 years old and we still all use it. Just because something is old does not mean that it is no good. It just means it works. Microfilm is analogue, it is physical and it is secure. However, with the latest microfilm scanners you can turn microfilm into a digital format whenever you want to – the best of both technologies.”
If you can smell vinegar around your microfilms or negative collection, you have a problem that needs addressing urgently. The extent of that problem can only be determined by having your films assessed. While proper storage can slow the degradation, the film will eventually need to be duplicated on to a modern preservation material or digitised. Here at NZMS we are seeing more and more collections sent to us for assessments and reformatting where the film has degraded to the point that the cost and ability to recapture has increased markedly or at worst your information is irretrievable. We have devised a special method – unique in New Zealand – of duplicating buckled films that means they can be digitised.
One thing you simply can’t do if you have responsibility to ensure your collections are available for future generations is to shut the cupboard, or close the drawer, and hope for the best.
We appreciated the advice in the following resources in putting this document together:
- Reilly, J.R. (1993). Image Permanence Institute storage guide for acetate film. Retrieved from: https://www.imagepermanenceinstitute.org/webfm_send/299
- https://www.nedcc.org/free-resources/preservation-leaflets/6.-reformatting/6.1-microfilm-and-microfiche – Good historical summary of MF
- http://archives.govt.nz/sites/default/files/iod/app20180032_nzqa_appraisal_report_public.pdf (Case study: The impact of loss, and the process around disposal in accordance with Public Records Act (2005))
- http://www.micrographics.co.nz/digitising-glass-plates-for-the-sir-george-grey-special-collections-with-auckland-libraries/ (Case study)
- https://www.theatlantic.com/technology/archive/2018/07/microfilm-lasts-half-a-millennium/565643/ (Opinion piece about the value of content contained on microfilm & contextuality gains vis-à-vis a typical “google ‘ search)
- View the suite of our Micrographic services here – http://www.micrographics.co.nz/microfilm/overview/