Journal of Film Preservation - FIAF

The Color-Restoration of Faded
Color Film Prints
Restauration de films en couleurs
La dégradation par effacement progressif de
l’image des films en couleur, étant très
répandue et rapide, est devenue une source
majeure de soucis. Fabricants de pellicule,
exploitants et conservateurs unissent leurs
efforts de recherche pour l’amélioration de la
stabilité des images en couleur. Les
fabricants ont amélioré les procédés
chimiques de tirage et de développement afin
de retarder le processus de dégradation, les
experts en conservation se concentrent sur
les conditions de stockage et de préservation.
Différentes méthodes tendant à corriger la
couleur au moment du copiage ont été mises
au point mais impliquent des procédés aux
technologies complexes et coûteuses. Depuis
les années 70, les auteurs de l’article
développent un ensemble de mesures de
restauration de la couleur. Il s’agit d’un
traitement chimique approprié visant à
atténuer ou intensifier de manière directe et
sélective, les ombres subsistantes dans le but
de restaurer les couleurs et d’en rétablir
l’équilibre original. Les inventeurs de la
méthode espèrent obtenir de bons résultats
de ce procédé qu’ils estiment rapide, bon
marché et fiable.
Xu Jianhe and Ge Xiangbei
The widespread and rapid fading of coupled developed color images has
led to grave concern from those involved with the conservation of
photographic resources. For a long time, experts in the fields of
manufacturing, production and conservation of film have been searching
for an effective means to improve the stability of color images. Film
manufacturers have concentrated on modifying the nature of the color
coupling and developing agents in order to reduce the rate of color
fading, while film preservation specialists have focused on the
improvements in the storage environment in order to extend the effective
life of film resources. Also, a number of remedial processes have been
developed to address this problem. In cases of moderate fading, color
retiming, or a process for three color separation (with contrast
adjustment made in each of the three individual color records) and
recombination has been successfully employed. In the late 1970s, Kodak
developed a duplicate mask technology to restore faded color images.
Nevertheless, all of these methods of color restoration are based on
complex technology, and are slow and costly. Beginning in the mid-
1970s, we worked out alternate methods for restoring color film.This
method is a chemical treatment which directly and selectively intensifies
the color in faded negative, which allows the restoration of original color
balance. This method of color restoration had produced good results,
and is characterized by high speed, very low cost, safety and reliability.
1. The Process of Color Restoration
The characteristic fading of color film that has been stored in darkness is
mainly hydrolytic reductive fading. Reductive decomposition takes place
when the cyan, magenta and yellow colors in the coupling-developed
image are subjected to attack from hydrogen ions (H+), hydoxy ions
(OH- ), acidic sulfite ions (HSO3-) and thiosulfate ion (S2O32-) etc.
Also, a further reaction turns the dyes into leuco-compounds.
The chemical products which are the result of the decomposition of the
color-coupled dyes remain in the emulsion layer along with the
remaining dyes, if the gelatin base has not degraded and dissolved. This
provides the physical base for the process of restoration.
It is understood that during the development process of color-coupled
film, the developer is oxidized into quinone-diimine cation, which
combines with a coupler which has been dissociated into an anion, to
form a dye. If we can introduce an oxidation agent which can oxidize
the developer from the decomposition of dye into the quinone-diimine
cation, and let the coupler form an anion with the aid of the developing
bath, then we have already theoretically accomplished the restoration of
40 Journal of Film Preservation / 58/59 / 1999