Fading of Colour Photographic Dyes III-Isolation and Identification of Reductive Fading Products of 1-phenyl-3-methyl-4-aza-(p-diethylaminophenyl)-2-pyrazoline-4,5-dione by Bisulphite

Kurosaki, Tomohiro; Itamura, Sumio; Rokutanda, S.; Teramoto, T.; Miyagawa, Tsugio

doi:10.1080/00223638.1988.11736971

Cited by 4 publications

(4 citation statements)

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“…4 Historically, the azamethine dyes used in the magenta record possess poor light stability relative to those used in cyan and yellow, and much photophysical and photochemical work has been carried out to try to explain this. [5][6][7][8][9][10] However, most of this work has focussed on using dilute solutions where fluorescence and triplet state quantum yields are less than 10 À4 and 0.04, respectively. 11 In an exposed and fully developed photographic coating the dyes reside at fractional molar concentrations in oleophilic droplets with diameters on a sub-micron level, which are dispersed in gelatin.…”

Section: Introductionmentioning

confidence: 99%

Aggregation of azamethine dyes on hydrated glass surfaces: An evanescent wave-induced fluorescence study

Parmar

Rumbles

Winscom

2002

Phys. Chem. Chem. Phys.

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The formation of luminescent aggregates of two pyrazolotriazole azamethine dyes in bulk solutions and at hydrated glass surfaces has been investigated using steady-state and time-resolved fluorescence spectroscopy as well as evanescent wave-induced fluorescence spectroscopy (EWIFS). Bulk measurements of dye A in methylcyclohexane, acetonitrile and dibutyl phthalate show that it exists as a molecular entity with fluorescence decay times in the sub-picosecond regime. However, in methylcyclohexane, dye B forms aggregates that possess fluorescence decay times in the nanosecond regime. Nevertheless, EWIF studies show that both dyes form luminescent aggregates at the interface between hydrated fused silica and methylcyclohexane, and hydrated flint glass (LASF3) and dibutyl phthalate.

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Section: Introductionmentioning

confidence: 99%

Aggregation of azamethine dyes on hydrated glass surfaces: An evanescent wave-induced fluorescence study

Parmar

Rumbles

Winscom

2002

Phys. Chem. Chem. Phys.

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“…This radical ion pair then disintegrates to destroy the dye. 6,19,20 It should be noted that ED and EA can also quench the excited state of the dye. Eqns.…”

Section: Light Fadementioning

confidence: 99%

“…4 Historically, the azamethine dyes used in the magenta record possess poor light stability relative to those used in cyan and yellow, and much photophysical and photochemical work has been carried out to try to explain this. [5][6][7][8][9] In a particular colour layer of an exposed and fully developed multilayer photographic coating, the dyes reside at fractional molar concentrations in oleophilic droplets of diameters on a sub-micron level. Prior to processing, these droplets, which are dispersed in gelatin using a suitable surfactant, contain the corresponding dye couplers (precursors).…”

Section: Introductionmentioning

confidence: 99%

Light stability of pyrazolotriazole azamethine dyes at oil/aqueous interfaces

Parmar

Rumbles

Winscom

2005

Phys. Chem. Chem. Phys.

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Film and dispersion coatings of two pyrazolotriazole azamethine (PT) dyes are used to study the effect of increasing the surface-area-to-volume (SA : V) ratio of the oil/aqueous (solvent/gelatin) interface on nonoxidative and oxidative fade characteristics. High concentration solutions of the dyes in a poly(vinyl acetate)dicyclohexylphthalate mixture as solvent are coated on glass substrates with a gelatin overcoat to produce thin film coatings and are also dispersed in gelatin to create "oil-in-gelatin" dispersion coatings. It is calculated that the dispersion coatings possess a SA : V ratio of approximately 20x greater than the film coatings. In nonoxidative fade conditions both the film and dispersion samples possess similar quantum yields of fade, implying that the presence of a solvent/gelatin interface does not significantly affect any electron transfer fade mechanisms. However, in oxidative fade conditions increasing the SA : V ratio of the interface by 20x leads to an increase in the quantum yield of fade of only a factor of 1.5-2. This disproportionate increase in the fade kinetics in dispersion coatings is explained by a kinetic scheme modelling oxygen diffusion through the coatings. It shows that the rate determining step for dye fade starts to become the diffusion of oxygen through the air/gelatin interface, and explains why changes in the SA : V ratio are not fully transferred to the quantum yield of fade.

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“…Over the years, commercial photographic and film material manufacturers have endeavored to improve the stability of their color stocks [4,7]. Simultaneously, chemists, imaging and conservation scientists, in collaboration with the global archival community, have initiated multidisciplinary research focusing on the characteristics of chromogenic dyes, their subsequent aging [8][9][10][11] and possible measures for the preservation and restoration of affected photographic and film heritage [12].…”

Section: Introductionmentioning

confidence: 99%

Digital Unfading of Chromogenic Film Informed by Its Spectral Densities

2023

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A material-based approach for the digital restoration of chromogenic photographic and film materials affected by dye fading is proposed. Through a digital reconstruction of the original optical properties, the proposed restoration methodology approximates the original color appearance in a non-subjective manner, thus improving the results compared to conventional RGB tonal re-adjustment of the film scan both in terms of quality and presumed faithfulness to original appearance. In order to do so, the degree of fading is derived from neutral black parts of the film’s image content, and the knowledge of the film material’s spectral densities is used to digitally reconstruct the colors corresponding to the material’s original dye concentrations and render them in an RGB space. For a comparison, results from conventional re-grading were adjusted to render them most similar—and thus comparable—to the results of the proposed spectrally informed digital unfading. The restored images obtained through spectrally informed unfading were deemed clearly superior in terms of color subtlety, color faithfulness and coherence.

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Fading of Colour Photographic Dyes III-Isolation and Identification of Reductive Fading Products of 1-phenyl-3-methyl-4-aza-(p-diethylaminophenyl)-2-pyrazoline-4,5-dione by Bisulphite

Cited by 4 publications

References 0 publications

Aggregation of azamethine dyes on hydrated glass surfaces: An evanescent wave-induced fluorescence study

Aggregation of azamethine dyes on hydrated glass surfaces: An evanescent wave-induced fluorescence study

Light stability of pyrazolotriazole azamethine dyes at oil/aqueous interfaces

Digital Unfading of Chromogenic Film Informed by Its Spectral Densities

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