With the recent worldwide COVID-19 pandemic Genus has been approached by several organisations, keen to release the key data held in their microfilms and microfiche. Talking to some of these organisations it has become apparent that the releasing of key data is not the only factor that concerns them. For some it is the worry of losing that key data by the decomposing of some of their older microfilms.
An interesting article has recently been written on the dangers of Vinegar Syndrome for collections of Acetate based microfilms. Written by Ida R. Ahmad, UCL it highlights an area that has been discussed before – Historical films may be decaying much faster than we thought thanks to ‘vinegar syndrome
In the 1980’s the base layer of all microfilms was changed from Acetate to Polyester. All the manufacturer’s made this change, although this change took a full decade. However, from the mid 1920’s until this point Acetate was the most common base layer format. As detailed by a 2003 New York State Archives article – Acetate Microfilm – there are two main issues with acetate based microfilm – information loss and off-gassing. Both are correctable, but only planning and quick action will help minimise the potential damage.
As the acetate base degrades, most commonly caused by being stored in warm and humid environments, acetic acid is created which has a vinegar like smell, hence the name of Vinegar Syndrome. The formation of acetic acid causes the base layer of the film to shrink whilst the emulsion layer maintains its normal size. In extreme cases of deterioration, warping, curling, buckling, embrittlement, and blisters (also known as channels) start to appear on the film.
One key question asked by many microfilm collection holders is how to establish whether the film they have is acetate-based or the much safer and modern polyester base. The premise of anything created after the 1980’s is safe, is not accurate enough. One of the simplest ways to find out which base layer you have is to try and tear the film with your fingers. Acetate based film will tear relatively easily whereas polyester film will not. There are more ways to determine the difference, such as the opaqueness of the side of the film and whether the unwound film curls or not. If you have any doubt at all then our technical staff at Genus would be very happy to help and advise. We can use more advanced methods to determine the difference such as polarisation tests and Acid detection test strips.
If the microfilms are not in too serious a condition, then the solutions are relatively simple. You can make a new copy of your microfilms onto either brand new polyester based silver or diazo copy film. At Genus we have the equipment to make these copies for you. The more popular method is to scan your microfilm collections. However, if you need to continue to hold a microfilm copy for historic or legal reasons and you are worried about the inherent issues of digital images as an archival medium then you may be hesitant about scanning Microfilm. We have written a number of blogs on this subject –
If your microfilm collection is in a fairly good condition then you may want to consider studying the Rochester Institute of Technology, Image Permanence Institute paper entitled “IPI Storage Guide for Acetate Film”
For an excellent background Standard on Microfilm production in its entirety the AIIM/ANSI Standard MS23 – 2004 Recommended Practice – Production, Inspection, and Quality Assurance of First-Generation, Silver Microforms of Documents is an excellent starting point. You can buy it either from ANSI or AIIM
At this delicate time in the world you will be considering freeing up the mission critical information you hold on microfilm. At the same time you should also consider preserving that microfilm carefully too. If you have any questions on anything to do with microfilm, then please come and talk to us at Genus.