Poor
Chemical Processing and Image Instability
-
Deterioration
can be accelerated when photographs are poorly processed (ie. the use of
exhausted fixer) or inadequately washed (failure to rinse the residual fixer
from the film or paper)
-
When residual
fixer is left in the photograph it can result in the image, binder and support to
turn yellow or brown (a sepia coloured toning) and the silver image to fade - sometimes
referred to as sulfiding. This can be caused by residual sulphur used in the washing
process or also can be caused by sulphur in the air.
-
Conversely, if
a photograph is not fixed long enough, it becomes more light sensitive and may
darken when exposed to light.
-
Redox
(Oxidation-Reduction): typically occurs in photographs containing silver image
material. In the oxidation-reduction process, the silver in the image is
attacked by oxidants in the atmosphere (e.g., pollutants, ozone, paint fumes).
This forms new colorless silver compounds. During the reduction part of the
process, the silver may be turned back into metallic silver but deposited in a
different location in a different physical form. Resulting damage can include
silver mirroring, loss of detail, and fading of the image.
Next