Development of rapid processing methods is described mainly in a view-point of processing solution and equipment, from about 1930 to 1962.

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This is one of series of study which enables to put the title on the colour film. Paraffin and waxes of good quality are coated on the film. After the drying, the typographic latters are pressed on the wax layer in order to remove the wax on the title parts. The film is dipped in a alkaline solution of sodium hypochlorite, meanwhile the dyestuffs under the letters are bleached, the gelatin and silver halide are decomposed. After washing out the decomposed products, wax and paraffin are removed by organic solvent (carbon tetrachloride and so on) and the film is finished by washing with water and by drying to have a clear superimpose.

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Measurement of characteristics (Sensitometry) of diazo papers that are used generally in duplicate, is described in this paper.
As diazo papers generate posi-posi printings that make line work drawings an object, the foundamental point of view for characteristics is similar to it of photo printing papers, but latitude is severer in the cause of parameters, original and back ground density of copies, etc. The measuring results of typical moisture and gas dev. type diazo papers, there are on sale; are shown in the following table.
Moisture type Gas dev. type
Max density 1.07 1.32
Min density 0.12 0.11
Gamma 1.05 1.50
Latitude At over exp 1.41 1.78
At under exp 1.62 1.22
Color Purple Blue

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It was found that when a photographic emulsion layer containing a certain diffusion-fast pyrazolone coupler is color processed, in certain cases the dye formation may not be complete. The phenomenon may be observed sometimes in the case of the processing by a mono-bath bleach-fixing solution containing the EDTA-Fe^III complex as a oxidizing agent, but not in the processing by the combination of a ferricyanate bleaching solution and a fixing solution. Such an incompleteness of dye formation depends apparently upon the bleaching process, but it results from the midway stopping of dye formation merely in the color developing process.
This irregular-dye-fromation can hardly be affected by the ordinary change of the sort of the developing agent and the quantity of sodium sulphite in the developing solution. It can also not be caused by various agents added to the emulsion, but depends upon the structure of couplers. The structure of couplers apt to show the phenomenon was made clear.

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The mechanism of magenta dye formation was studied from the view point of the irregulardye-formation observed in the color development of a color film containing a certain diffusion-fast pyrazolone magenta coupler.
A dye formed from a diffusion-fast pyrazone magenta coupler reacts at pH 10 with the coupler in a gelatin solution even at 20°C, and easily produce a leuco dye. This character is more remarkable for a diffusion-fast coupler than for an in-developer type coupler (1-phenyl -3-benzoylaminopyrazolone), and depends upon the micelle condition of the coupler in gelatin. The fading velocity and its rate constant, however, are not related to the irregular-dye-formation and the latter has not relation to also the reduction of a dye by developing agents or sodium sulfite in an ordinary developing solution.
It was clarified that couplers with certain structures sometimes produce stable intermediates, leuco dyes, which can not be sufficiently oxidized to dyes only by the oxidation products of a deveping agent. The irregular-dye-formation was found to result mostly from such an origin.

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