Journal of Film Preservation - FIAF

Table 1: Results of oxidation-development
dual-bath color-restoration technology
(4) This process increases the color stability of the
dyes significantly. A print treated in 1976 which has
been stored at room temperature has now retained its
color for over twenty years without discernable
decomposition or fading.
(5) The oxidation-development color restoration
process does not spoil the original dyes. Thus, if a
film does not respond to the color restoration
process, the original image is not affected.
3. The Oxidation-bath Chemical Color
Restoration Process
If we analyze the principle of coupling development
of an image, we can see that it is the alkaline in the
developing bath - that is, the hydroxy-radical –
which permits the coupler to gain an electron and
form an anion, and then to combine with the cation
of the developer to form a dye. In the above
described oxidation-development process there are
numerous unnecessary components. In fact, our
process only utilizes the oxidant and alkaline
components.
According to our research, only a strong oxidant
together with an alkaline substance are sufficient to
produce an oxidative color restoration solution for
water-soluble emulsion film prints Our experiments
demonstrated that an oxidant solution alone not only
cannot restore faded color, but actually induces
fading of the indo-aniline cyan layer of the
image.Trisodium phosphate, hydroxides, sodium
carbonate and other alkaline substances at high concentration can
restore the cyan layer. But the mixture of the two solutions produces a
very strong oxidative-reductive agent for the faded color image.
Evidently, this dual solution produces an “additive” reaction. If we add a
suitable quantity of formaldehyde, the emulsion layer will not be
dissolved by the process, even at relatively high temperatures. Thus,
restoration of water-soluble cine-color prints can be accomplished by use
of a suitable combination of oxidant, alkaline substance and
formaldehyde (see Photograph 2).
A secondary value of this restoration process is that it has high stability
and strong buffer characteristics. Variation of the content of the oxidant
and alkaline solution within a certain range will not influence the result
of the color restoration process or elongate the processing time. This
treatment is quicker and simpler than other methods of color
restoration, requiring only a 3-5 minute treatment in solution, followed
by a 6 minute water wash cycle.
It should be emphasized that water-soluble color cine film positives
found in archives come from various manufacturers, have been produced
42 Journal of Film Preservation / 58/59 / 1999