| 摘要 |
725,667. Photographic process. KODAK, Ltd. Jan. 21, 1953 [Jan. 21, 1952], No. 1826/53. Addition to 655,274. Class 98 (2). A method of photographic reproduction comprises the exposure of a substantially unhardened light-sensitive silver salt emulsion layer to a two-tone subject by the reflex-printing method, develpment in the presence of both a tanning and a non-tanning silver halide developing agent to develop a silver image in hardened colloid in the highlight regions of the layer and also a silver image in substantially unhardened colloid in the shadow regions of the layer and the transfer in the presence of moisture of at least a thin stratum of the shadow regions of the layer to a support, which may be absorbent. Either or both of the developing agents may be incorporated in the emulsion or in the alkaline solution used in the development step. The tanning developing agent may be one of those described in Specification 655,273, and the non- tanning developing agent may be 4-methoxy 1 - naphthol, N-methyl-p-aminophenol-x-sulphonic acid, p - hydroxyanilinomethanesulphonic acid, pyrogallol dimethyl ether, 1: 8 - dihydroxy - naphthalene, 2: 4 - diaminophenol, 5 - amino - 2 - hydroxytoluene sulphate, 2: 5 - diamino - toluene sulphate, p - phenylenediamine, p - aminophenol, p - methylaminophenol sulphate, or isoascorbic acid. The non-tanning developing agent may be one capable of coupling with itself during development to form a dye, e.g. 4- methoxy-1-naphthol or 1: 8-dihydroxynaphthalene. The proportion of tanning to non-tanning developing agent may be between 60: 40 and 65: 35. In an example, paper is coated with a substantially unhardened gelatino silver halide emulsion to which has been added aqueous saponin solution, a dispersion prepared by pouring a dibutyl phthalate solution of 3: 4-dihydroxydiphenyl into a vigorously stirred solution of gelatin containing saponin, and a similar dispersion containing 4-methoxy-1-naphthol. Development may be effected with an aqueous solution of sodium carbonate containing urea or other gelatin softener such as formamide, ethylene chlorohydrin, or sodium nitrate, and, after removal of excess moisture, successive transfers are effected. The last copies may be quickly heated in the presence of moisture to increase the optical density. The tanning developing agent only may be incorporated in the emulsion, and the non-tanning developing agent incorporated in the alkaline solution. A mixture of non-tanning developing agents (e.g. 2: 4-diaminophenol and isoascorbic acid) may be used.
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