Silver Gelatin Developing-Out (DOP), Resin Coated (RC), Photo-Stat

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Date initiated January 2012
Contributors Amy Brost, Stephanie Watkins

Silver Gelatin Developing-Out, Resin Coated (RC), Photo-Stat[edit | edit source]

Papers with silver sensitized emulsion layers were used widely for pictorial image making, documentation, and copying processes into the 21st c. Silver-gelatin's market dominance was replaced by digital image technology. Silver-gelatin processes are still used by photographic artists.

Historical Facts[edit | edit source]

Invented: 1871, Richard Leach Maddox; 1878 improvements, Charles Harper Bennet
Important Development Dates:

  • 1874 Commercial production of gelatin for Developing-Out Papers (DOP)
  • 1885 Commercial coating machines
  • 1894 Baryta layers added to commercial Developing-Out Papers (DOP), 1900 introduced to Kodak papers

Historic and Contemporary Practitioners: As one of the most widely used processes in the 20th c., just about anyone working in this period did work with silver-gelatin at one time or another whether amateur, professional, or copyist.

Identification Characteristics[edit | edit source]

Image layer[edit | edit source]

The image is within the emulsion layer. It can either be partially within the paper structure as with printing-out processes, or on top of a baryta layer as with developing-out processes.

Color[edit | edit source]

Pristine silver gelatin printing-out photographs can range in color from warm browns to cool purples because of the nature of the development of the photolytic silver strand. Pristine silver-gelatin developing-out photographs are generally monochromatic, blue-black and white in appearance. Both processes can be toned to different colors with the addition of a toning process during development, using other minerals such as selenium or gold.

Support[edit | edit source]

Silver-gelatin emulsions can be applied to numerous types of substrates including paper. Paper substrates used in direct contact processes are usually sized to withstand the numerous immersion baths required during processing.

Analysis[edit | edit source]

Basic Process Overview[edit | edit source]

Image creation in all silver halide processes involves sensitizing a substrate with silver halide, and exposing it to light, which breaks the bond between the silver and the halide. The silver ion is then reduced to become free silver, which creates the dark areas of a photographic image.

The silver gelatin developing-out process involves exposing and developing a negative, which can be placed into an enlarger. Light is passed through the negative onto sensitized photo paper, which is then chemically developed-out. The exposed paper is developed (to reduce the silver ions), stopped (to stop the reduction/darkening), fixed (to remove the unexposed silver salts), and washed (to remove any trace chemicals from the previous baths).

Housing and Storage Considerations[edit | edit source]

  • Silver gelatin prints should be stored in good quality paper-board folders, to protect from light, dust, and handling. They can also be stored in plastic film folders and sleeves, such as uncoated, unplasticized, virgin polyester terephthalate, poly(ethylene), and poly(propylene). Materials that pass the Photographic Activity Test (P.A.T.) will provide suitable housing for these types of photographs.
  • An ideal temperature and humidity are 68 degrees F (20 degrees C) +/- 2 degree drift and 50% +/-5% variation over 24 hours.

Emergency Recovery[edit | edit source]

Handling wet paper can cause damage such as nicks, abrasions, and tearing. Mold can develop on or within the papers and emulsion layers.

Other Considerations[edit | edit source]

  • Moisture and humidity can cause these photographs to attach to themselves and other surfaces. Refer to the Releasing, Detaching, Separating methods section.
  • Moisture and humidity, especially if high or sustained, can promote mold growth.
  • Gelatin photographs, especially very glossy or ferrotyped surfaces can easily be scratched and marred.
  • Prints may be chromogenic or be hand-colored black-and-white prints.
  • Baryta layers may be non-existent, very thinly or thickly applied in both home/boutique-made and commercial made photographic material.
  • For Helpful Treatment Techniques, refer to the entirety of the Treatment Procedures listed within the PMCC WIKI.

Further Reading[edit | edit source]

Historic Material[edit | edit source]

Contemporary Practice[edit | edit source]

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Cite this page: Photographic Materials Group Wiki. 2024. Photographic Materials Group Wiki. American Institute for Conservation (AIC). Accessed [MONTH DAY YEAR].

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