Preserving Cellulose Acetate Negatives in Mali: The Use of A-D Strips for Monitoring Degradation

by Heida Q.S. Shoemaker, Photography Conservator

Great Mosque at Djenné, Mali; photo by H. Shoemaker, 2011

The climate in Mali, West Africa is hot, and fluctuates between constant dampness in the wet season and long periods of bone-dry days. The red earth of the surrounding landscape lays on the roads of the cities, the walls inside the houses, and on every exposed surface possible. This climate is harsh, yet within it are collections of unique, historically and artistically important, incredible works of art which comprise the photographic archives of Malian photographers.

The preservation of these photography collections is the goal of The Malian Archive of Photography, a two-year NEH project awarded to African Art Historian Dr. Candace Keller, from Michigan State University. The goal of the project is to clean, scan, catalog, and house 25,000 negatives from each collection of four Malian photographers. I was invited to join the project as the Photography Conservation Specialist. Our team, consisted of myself, Dr. Keller and Dr. Ethan Watrall, Associate Director of MATRIX Center for Digital Humanities. We arrived in Bamako, the capital of Mali, in October, to train the technicians and students, who are photographers in their own right, in cleaning, scanning, cataloging, and housing the negative archives. This group will be involved in this work full time for the next two years - cleaning, processing and preserving 100,000 negatives total.


Bamako, the bustling capital city of Mali, is an important center of contemporary photography in Africa. Malian photographers today were influenced by a core group of portrait photographers who opened studios in Mali in the 1950's-60's, and were prolific, vital artists for many decades.

One of the most well-known, and one of the four photographers that The Malian Archive of Photography is focusing on, is Malick Sidibé. Sidibé opened his photography studio in the Bamako neighborhood of Bagadadji, in 1962. He set up studio shots here – of friends, athletes, engaged couples, professionals – and also went to and recorded dance parties of the 60's, and street scenes of everyday youth in the thriving capital.

Abdourahmane Sakaly (1926-1988), the other focus of the work this year, was active in the 1950's-80's. As a young man Sakaly learned photography at a studio in Senegal. Moving to Bamako in 1956, he set up his own studio and began to specialize in photographing the social circles of military officers and the growing middle class. After Mali’s independence and with the subsequent growth of the bureaucratic class, his studio became very successful.


Environmental Monitoring

The medium-format cameras used by Sakaly, Sidibé, Adama Kouyate and Tijani Sitou (the latter two collections will be addressed next year) starting in the 1950's-60's and spanning the decades of their careers, produced thousands of black & white cellulose acetate negatives.

These negatives are stored in varying conditions, mostly in the photographers' private homes, photography studios and offices in various cities in Mali. They are primarily stacked in the cardboard Kodak or Fuji film boxes they were bought in, usually with no interleaving or envelopes. Daytime temperatures range from 75º-110ºF (24º-42ºC), RH fluctuates between 30%-70%. Due to limited resources, air-conditioning is very rare, fans may be used off and on, but not dedicated specifically to photograph storage.

I knew that these conditions could be detrimental to the cellulose acetate negatives over time, which are well known to deteriorate dramatically with age, accelerated by high temperature and humidity. Vinegar syndrome, tackiness, shrinkage, severe distortion and yellowing are the tell-tale signs of cellulose acetate deterioration.

The warning sign was given to me by one of the technicians only a month before our trip, when he declared that he had seen negatives sticking to their plastic enclosures (part of a re-housing project focusing on one of the four photographer's archives initiated by Dr. Keller in 2011). Inquiring further, the vinegar smell had also been detected in the boxes of negatives, indicating the release of acetic acid by the degrading film.


A-D Strips

I contacted IPI at this point, and had many helpful, thorough discussions with Senior Research Scientist, Douglas Nishimura, concerning the situation and suggestions of steps to take. The first and most obvious one was the use of A-D Strips for monitoring the degree of deterioration of the cellulose acetate. A-D Strips, developed by IPI, were a simple, visual tool that the technicians could be trained to implement and monitor with a few quick lessons and demonstrations. The instruction book even had French translations!

With my instruction, A-D Strips will be placed in a sampling of 30 boxes from each of the two collections of negatives. After two weeks (the time indicated by IPI for optimum color change, based on specific room temperature on location) they will be observed for changes in color, which would indicate the presence of the acidic vapor given off by decomposing acetate film.  A change from blue to green would indicate “deterioration beginning, cool storage recommended”, yellow would indicate “shrinkage and warping imminent, possible handling hazard, freeze immediately and copy!” Observations of color change will be recorded in a simple chart, and relayed to me so that I can determine the degree of active deterioration present in the sampling. I will then set priorities for further actions. One of the obvious priorities is to change the enclosures of the archives processed in 2011 from plastic to paper, and paper envelopes are being used for the present housing project.

More importantly, future actions should ideally include improving the environmental conditions of the negative storage areas to cold, or at least cool storage. Negatives in critical condition should be isolated in frozen storage. Although this seems daunting, the quantity of negatives has already been limited by the project, and proper housing conditions and a dedicated storage area have already been put in place. Improving the environment in terms of temperature is the next clear step. Unfortunately, the present funding for the Mali Photo Archive project does not include future allocations for improvements to storage conditions. Although it is reassuring that the negatives are being preserved digitally through the scanning procedure, the future of the negatives themselves is uncertain without further action.

Please contact me at with suggestions, ideas, or donations for the next steps for the preservation of this important collection of Malian photography.