Ilfochrome

The Ilfochrome (known also under the name of Cibachrome ) is a photographic process of Tirage color since a invertible Film (this last often in the form of a Diapositive color) produced by Ilford Photo.

History

The processes of pulling color by destruction of pigments, also indicated like “processes by discoloration” or “bleaching”, date from the beginning of the XXe century, with the Utocolor process of Dr. J.H. Smith introduced in 1906 with Zurich, then the process Gasparcolor de Bela Gaspar in 1933. This technique is thus older than the techniques with coupling of dyes of the Type C or Type R, also called chromogenic techniques, which go back to 1936.

Ilfochrome, marketed since 1963, is the last representative of this tradition. It was launched by Ilford in partnership with the Swiss firm Ciba-Geigy Photochemie under the name of Cibachrome . Ilford and Ciba-Geigy produced each one their own process before this bringing together. After the repurchase of Ilford by International American Paper, Ciba-Geigy required so that this process to which it did not take any more share change name. Cibachrome thus became Ilfochrome . The first term (or its short cut, Ciba ) however remained in the current language.

Interest

Ilfochrome pullings are famous for their qualities of filing, and their resistance to the attacks of the Sun.

The white of the Ilfochrome tests are also famous for their purity, i.e. for the absence of this “dirty” aspect of the white areas which one sometimes observes on pullings color since negative.

Lastly, one praises the Acutance épeuves Ilfochrome, which would not be prone to the dispersion of the light which affects the tests since negative color.

Principle

It is about a process of positive pulling making it possible to obtain a test directly starting from slides ( proceeded positive-positive ), contrary to the internégatif tranfert or the additive proceeded of Type R sometimes used by the laboratories for pulling since slides.

Paper

Ilfochrome pullings are carried out on a basis of Polyester stable tri-acetate, therefore with strictly speaking a plastic base and not paper. The coloured pigments are included in this base and are selectively bleached during the treatment, which is the opposite of the additive processes for which the pigments are contained in the chemistry of the treatment. Not-talk, “paper” Ilfochrome is brown dark. More the hard exposure, more the test after treatment will be clear, which is anti-intuitive for the operators accustomed to black and white pulling.

The Pigment S used, called Azo, present an important saturation of the colors and are close chromatically to the Cyan, magenta Jaune and of reference.

Ilfochrome paper can be chechmate or brilliant. It includes/understands 9 layers (in addition to the support and paper) on the basis of the base:

support
paper RC polyester tri-acetate
layer of emulsion sensitive to the red with dye cyan
layer of emulsion sensitive to the red without dye
interlayer of gelatin
layer of emulsion sensitive to the green with magenta dye
layer of emulsion sensitive to the green without dye
transition course of mask
layer of emulsion sensitive to blue with yellow dye
layer of emulsion sensitive to blue without dye
varnished/glazing

Process

The process of Ilfochrome pulling marketed for the laboratories amateurs (P30) includes five phases:

the development by a revealing black and conventional white,
a first rinsing with water,
bleaching by bath of acid to remove the pigments or agents nonexposed dyes,
the fixation of the test,
the washing of the test to water, generally runs because of the support tri-acetate and not paper.

Processes P3 and P3X conceived for the automatic machines with maintenance of the professional laboratories require intermediate baths of washing in supplement. The process P4 Ilfochrome Rapid as for him is conceived for reduced times dryness-with-dryness, always for a professional use, but it does not act any more Cibachrome (although it is always about a process by discoloration).

See too

On Wikipédia

Treatment photographic E-6
Pulling
Ilford Photo

External bonds

Page of the Ilford site devoted to Ilfochrome

Random links: