| The collection of nitrate and diacetate negatives
was produced by an archaeological foundation surveying during the years 1928 to
1939. When received by the Arizona State Museum in 1951, the negatives were place
in brown kraft envelopes and stored, unnumbered in a large metal filing cabinet.
For more than thirty years the negatives remained unincorporated with the main
body of the ASM Photography Collection. An inventory in recent years confirmed that
increased use had degraded the scant organization of the collection and had placed
the collection at increased physical jeopardy. Fortunately, the majority of the
nitrate negatives exhibited mostly stable emulsions with only occasional discoloration.
Because of the instability of aged negatives made on cellulose nitrate supports,
it was imperative to copy the collection before distortion of the images occurred.
The nitrate and diacetate negatives were removed from storage and placed in
a large workroom. The negatives, in open drawers, were covered with sheets of acid
free tissue and polyethylene to help limit their exposure to light and dust. Workers
wore white cotton gloves to protect the aging film during handling. Tabletops were
covered with mylar to present a smooth work surface for materials.
Because entry to the room was from the museum exhibition hall, the door remained
closed for securing during museum visiting hours. Windows in the workroom were sealed.
Replaceable oil-free filters were applied to the air inlet vent to minimize the
dust entering from the building air conditioning system. Air exhausted at the ceiling
behind the cataloguer's workstation Temperature and humidity in the workroom were
monitored, showing an average temperature of 70o F and relative humidity at less
then 40% with extremes of 82o F and 58% rH during a five week period of local rains
and humid weather.
Temperature and humidity registered similar levels in the project darkroom.
Air was inlet to this basement facility near the ceiling above the level of the
technician's head. An old exhaust fan high in the opposite wall was ineffective
in circulating clean air through the darkroom. Fresh air entered and exited at the
ceiling level. The darkroom technician handled approximately 150 deteriorating negatives
per darkroom session, working at the sinks, developing tanks or vacuum frame. |
