Silver halide microfilm MAY last 500 years if it is manufactured, processed, and stored properly.
The question of how long CD’s will last, or how long they will be readable, appears to have migrated to the issue of Microfilm and its good and bad points.
As stated in the subject header:
Silver halide microfilm MAY last five hundred years if it is manufactured, processed, and stored properly.
The operative word in this statement is, MAY.
NOTHING LASTS FOREVER!
Microfilm is no exception. I have known of Acetate microfilm, which has become useless “non usable, nontransferable, non-retrievable” after less than 20 years of use. Its only value was to a rubbish bin as the emulsion had separated from the acetate substrata and on viewing images as small as single characters, e.g., an A could be seen floating on a sea of liquid silver particles.
Acetate film is inherently unstable. See various articles on “Vinegar Syndrome”. You may care to visit this site @ IPI – Image Permanence Institute – Rochester Institute of Technology for more information. There is more information available if you go to Google and ask the question “Vinegar Syndrome”.
I was not previously aware of this Vinegar Syndrome issue and up until 1998, I was, as a commercial bureau operator, still using Tri-Acetate film, as my film of choice. The film was available from Fuji and Agfa at that time and still is.
The rules for the long-term preservation of microfilm, which are storage at low temperature, 8-12 degrees Celsius, 30-40% relative humidity and darkness, are not the normal environment in which we find microfilm being housed, and or used.
It is not that CD’s are better than Microfilm, or that Microfilm is better than any other media. The question is what is the best media for my application, and do I understand the capabilities and limitations of the media I choose?
There are horror stories related to paper, film, microfilm, floppy disk, hard disks, Optical Disks, CD’s etc. etc. that should not have occurred had we been aware of the capabilities, and or limitations of the media in question and its particular environmental requirements for long-term (LE) preservation.
We now have the answer with Polyester Microfilm, or do we? We know that polyester is extremely stable, but I would bet my last dollar that in time to come we will have a horror story or two to tell because we believe polyester film is the ultimate media. The polyester substrata or base material may be the ultimate because of its stability but what about the adhesion or binder material, which holds the emulsion to the substrata and what about the stability of the silver gelatin emulsion.
OK, the polyester substrate does not shrink or expand to any degree with varying temperatures and relative humidity, but guess what, the binder and the emulsion do. What happens when the tensions between these two are so great that the binder and the emulsion layers tear themselves away from the indestructible polyester substrate?
Let us not argue, if microfilm is, or is indestructible, no, it is not, nor can it be as everything has a finite lifespan. Nothing lasts forever!
We need to be aware of microfilm’s capabilities and its limitations and make certain we do our best to preserve the media and more importantly, the information contained to suit our needs.
My ten cents worth!
Laurie Varendorff ARMA
Laurie Varendorff, ARMA, a former RMAA Western Australia Branch president & national director, has been involved in records management and the micrographic industry for 37 years. Laurie has his own microfilm equipment sales & support organisation – Digital Microfilm Equipment – DME – and a – records & information management – RIM – consulting & training business – The Varendorff Consultancy – TVC – located near Perth, Western Australia, & has tutored & written course material in recordkeeping & archival storage & preservation for Perth’s Edith Cowan University – ECU. Phone: +618 9286 3705; mobile: +61 417 094 147; email @ Laurie Varendorff
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