Evaluation of a Private Film Collection
for the "Vinegar Syndrome" with
Present and New Techniques

by Morten Jacobsen
Denmark

35 years is a long time for a human being. It is about half his life. Starting out at 22 making films as an amateur and idealist shooting films with friends and foe, going to festivals and sometimes winning that is fun. Turn it into a professional career and you begin to stack your tins. You continue to do that and it become part of your life that follows you as your luggage does when travelling.

You tend to forget you have a collection because a lot of what you have done has already become history a few moments after it was screened for the first time and then forgotten.

But you still drag your luggage with you as long as you live because you don’t have the guts to throw it away and some of it is even worth seeing again after a few decades. Family stuff mainly and perhaps some that won prices.

Film as luggage is fragile and conditions of storage less than ideal. They are still in the same tin and sometime the tin is rusty outside, sometimes inside and you never have the guts or time to open the tins.

Then one day you pull yourself together and begin to open tins. You could say you were forced to do so because it is part of your next 35 years, and trust me 35 years is the onset point for the vinegar syndrome.

As my life slid towards new opportunities in the seventies, the trend was to serve film libraries with film spools and cans; in the eighties, with the introduction of video distribution, I moved on to film storage; and the nineties towards preservation and observation of the problems that started more than 35 years ago. It seemed a unique opportunity to take your collection apart and see what the state of the art was.

70 rolls of film out of 200 were selected for the evaluation as being representative and with a destructive method 1 gram of film from each roll was dissolved in demineralized water. The pH value was ascertained and used for comparison with present and new methods of detecting the vinegar syndrome.

Is this small scale investigation indicative for large collections?

What is the condition of your collection?

Where is the auto catalytic point and what is it?

When do you have to copy?

When is the last chance?

The terms do not have to mean everything to you, all that matters is to know when to start copying the part of your collection affected with the vinegar syndrome. That can only be decided through monitoring and that is where I enter the scenario.

There is a saying, that a baker does not bake a "Danish" when he is off duty and a manufacturer of film cans does not "store" films in his own cans when he is off duty, still yet he preaches to his audience that they should do better. Shame on him. Now it is different as he is forced to look into his own collection, still very small, to see what the state of art is. Why this sudden interest? Well, quite frankly for the smell of vinegar (sorry, should read money), not for his own collection of 200 rolls, but in view of presenting an improved indicator. I have spent 7 years in introducing the Danchek and films are continuing to degrade and the 35 years barrier has been passed. It is said that the onset of the vinegar syndrome is 35 years I have visited archives 7 years ago that did not smell and recently revisited the same archives, and now they smell of vinegar! The archivist is beginning to realize he has a problem and he is getting more and more depressed because he does not know where to begin and where to end. To go after the smell is difficult because you can only say it smells in a given area. You have to start opening cans to find them and those that do not smell today may smell tomorrow. Back to my small archive. I started as a cameraman in 1960 and as a number of productions were my own they never left my "vaults". Well, that is because you store your films where you live and when you move you drag them with you to the next cellar or addict and they are still in the same can. Then at the end of 1997 I started taking them out of cans and 70 rolls were selected for evaluation. The rest were b-rolls and excess camera shots. The films were put in a heavy duty plastic bag with a test card with different types of indicators and hot sealed.

Establishing the pH value (destructive method)

0.5 grams of film was put in a cup with 50cc of demineralized water and the acidity was measured with Radiometer PHM 61 Laboratory pH Meter and adjusted with a buffer solution pH 7 and 4.01. The films were measured after 10 minutes, 1 hour and 12 hours. It seemed that the result after 12 hours was the most stable value.

Readings

After 24 hours, all 70 rolls were examined and the data taken down. This was repeated after 4 days, 7 days, 14 days and 1 month. It was of course evident that the strongly smelling film changed immediately and weak films took weeks to give a slight reading. I could list all films with data, but that would take too much space so I will start with the general picture after 1 month.

Can you trust the destructive method?

Yes and no. Yes if the roll of film is in one piece, but surprisingly enough, the indicator showed a different picture. There were many films in the pH 5-7 that had turned the indicator! The reason was found by winding the suspected rolls. They were, of course, composed of different films and you could find a few feet that could change the whole picture. Therefore the answer is NO.

Is it detrimental to store picture and magnetic sound?

In the collection there was a certain production where the picture was stored together with the magnetic tape (acetate) and in another tin the same picture alone and there was a significant difference in the pH measurement. The combo measured pH 4,3 and the picture pH 4,7.

So the answer is YES.

What about rust?

Metal film tins rust, that is a fact. They are most often rusty outside, but not inside. Then there are cans that are rusty both inside and outside – they are the ones with magnetic sound track in the can. Those with acetate could be just as rusty as those on polyester. So don’t try to persuade me that iron is not a catalyzer for the vinegar syndrome.

Is this small scale investigation indicative for a large collection?

Well, I visited an archive in the Mediterranean region recently and they had already done some selection of the heavily smelling films. The collection was 15,000 rolls and 300 rolls were taken into separate storage room. Well that is precisely 3%. Food for thought?

Indicators used:

As you can see from the scheme below, 3 different types of indicators were chosen. Danchek and AD-Strip are basically made up from the same dye, yet the Danchek carrier is silica for long term indication. The AD-Strip is supposed to react within a day and it does. The Danchek and AD-Strip reactions are identical and give the same reading. The New Danchek as a filter paper was tried and discarded, as it is a one hour test. The same dye was used on a "Non Ionic Polymeric Absorpent" which has the same surface size as silica. That proved successful and readings could be taken into areas where nobody could smell vinegar. It may not look impresive, but I can assure you there is a long way from pH 4,8 to 5,0.

Who wouln’t use the New Danchek?

Well that certainly depends on when you want to find your sick films. It is a compromise between time/money and ambition and it is easy to understand. However, you have a choice.

After 6 Months

Well something happened on the way to Rome. The New Danchek began to change above pH 5,0 to yellow and that is not acceptable. Some of you may recall JTS95 in London where J.C. Harthan and Michele Edge from the Manchester Metropolitan University presented the ultimate indicator and it looked impressive. I happened to see it published in The Imaging Science Journal, Vo. 45 1997 and rushed to copy it. It was pretty hard to take it out of the laboratory and into production as the dye used is Cresol Red which is red at pH 8,8 and yellow at pH 7,2. The trick was to add Sodium Hydroxide to build up a barrier and that is of course on excellent idea. However, that barrier is bound to break down sooner or later and that was recorded after 6 months. Nearly all films turned yellow. The article does not really say that, but the graphs as a matter of fact, indicates my point. I therefore, took measures as follows on my home page www.dancan.dk:

July 1, 1998 – Advice

Developing of indicators is a constant research. In cooperation with DANCAN intensive research, especially on the NEW DANCHEK has been performed as well as Manchester Metropolitan University and recently at the Technical University in Copenhagen, Denmark.

It is vital that any product presented represents safety in use. The recently announced NEW DANCHEK which changes its color from dark red to yellow works extremely well, but it was found to be considered a kind of TIME CHECK as well. This means that its color change is relative to time as well as to the amount of acidity. The indicator does sooner or later, anyhow change its color because it is the nature of that dye.

Therefore it has been decided not to market this product because the work of replacing the exhausted indicators at a later date will be too time consuming and too costly.

A further result of the research brought us back to the existing DANCHEK which changes from blue to yellow but substituting the carrier by a polymeric adsorbent which gives a much clearer color detection. It also keeps within the specified pH range which is from 3, 6 to 5,2. The readings are much easier to observe and is known as a safe product in use.

This announcement is meant to avoid confusion when in the future you will receive blue indicators.

Sorry for the inconvenience caused.

How good is a polymeric adsorbent?

Well, ladies and gentlemen, it is very good indeed, until you order a new batch of Amberlite and finds that it does not give the color readings expected.

Back to known techniques

Danchek in the version manufactured the past 7 years, has undergone some changes and improvements. It started as a vacuum formed device where the dyed crystals were glued to the inside, but since the stability of the glue was unknown, it was chosen to make a tool where several indicators could be moulded at the same time. This is the version seen below. The dyed crystals were separated from the outside by a thick piece of filter paper of highest quality for breathing, sniffing the vinegar easily. Color reading is not as "bright" as the Amberlike version, but I can assure you it works very well.

Light Stability

The Danchek indicator today is the improved version and light stability is superior to the version with Amberlike. A sample of Danchek has been in the window for 2 weeks with only little dye fading. You have to remember, at any color fades. It is now being experimented with light stabilizers for further improvement, so lets talk in 6 month about that.