PMG Photographic Processes

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Page Information
Date initiated January 2010
Contributors Amy Brost, Luisa Casella, Tatiana Cole, Kim R. DuBoise, Lisa Duncan, Monique Fischer, Saori Kawasumi Lewis, Amanda Maloney, Alejandra Mendoza, Laura Wahl, Stephanie Watkins


The Importance of Photographic Process Identification

Many photographic materials look similar, yet the chemistry behind them varies greatly. "Without detailed knowledge and understanding of the photographic processes used in making a given photograph, it is extremely difficult to determine the environmental conditions needed for the photograph’s long-term preservation, as well as the maximum light levels that should not be exceeded during display or exhibition. A detailed knowledge of the process chemistry, the processing and post-processing treatment, and the potential deterioration pathways is also needed when developing conservation and preservation treatments". [1].

"The identification of photographs and photographic processes based solely on visual and microscopic inspection of photographs can be used to answer more than 75% of identification questions successfully". [1].

Process Identification methodologies

Grafics Atlas

The Graphics Atlas from Image Permanence Institute presents a Photographic Process Identification Methodology and Controlled Vocabulary that analyzes the key identifying features of each photographic process. By observing and identifying the characteristics of each photograph, the unique combination of features leads you to a correct identification.

These key identifying features in this methodology are divided into three groups:

1. Object View

  • Primary Support
  • Image: Color/Tone, Quality
  • Formats/Mounting
  • Finishing Techniques
  • Deterioration Characteristics
  • Information Written or Printed on Object

2. Surface View

  • Surface Sheen
  • Surface Texture
  • Deterioration Characteristics

3. Magnification

  • Image Structure
  • Layer Structure
  • Deterioration Characteristics

The Atlas of Analytical Signatures of Photographic Processes

The Atlas of Analytical Signatures of Photographic Processesby Dusan Stulik and Art Kaplan is intended for professionals that may need to identify more unusual photographs and that may have access to analytical techniques to study them. It provides identification information in terms of:

1. Visual Signatures

  • Visual Characteristics
  • Microscopic Characteristics

2. Analytical Signatures

  • XRF
  • FTIR
  • Other Analytical Signatures relevant to each process

CAMEO of the Museum of Fine Arts, Boston, contains information and representative images of various photographic materials, including a short reference list. Gawain Weaver compiled a useful controlled vocabulary of photographic processes that includes a list of synonyms and specific products associated with photographic processes.

Photographic Processes

The list of photographic processes below is modeled after Bertrand Lavédrine's organizational structure, with permission.
The pages linked below aim to offer a baseline knowledge of photographic processes from a Photograph Conservator's perspective, and list links particularly relevant for the preservation and conservation of those materials.

Positives on Metal See also Cased Photographs




Positives on Glass See also Preservation of Glass in Photographic Materials

Ambrotype: Positive Collodion See also Cased Photographs

Color Screen Processes

Lantern Slides

Opalines, Opaltypes, Opalotypes

Positives on Plastic

Dye Diffusion Processes


Positives on Paper


Lightly Albumenized Salt Print

Bromoil, Oil-Pigment


Carbro, Ozotype, Anthrakotype, Ozobrome


Cyanotype, Blueprint, Pellet Print, Argyrotype

Collodion-Chloride Paper

Gum Bi/Dichromate

Platinum, Palladium

Silver Gelatin Printing-Out, Silver Gelatin Developing-Out, Resin Coated (RC), Photostat

VanDyke Brown, Kallitype, Brown Print, Sepia Print, Ferro-Gallic, Argentotype, Agyrotype

Mechanically Printed Positives on Paper



Photogravure (etching)

Woodburytype See also Carbon

Mechanically Printed Positives on Paper or Plastic

Computer-generated digital-sourced print See also Digital Prints

Negatives on Paper

Albumen Negatives

Salted Paper Negatives

Photogenic Drawings, Salted Paper Prints, and Calotype Prints

Negatives on Glass See also Preservation of Glass in Photographic Materials

Collodion Negative See also Cased Photographs

Gelatin Dry-plate Negative

Lantern Slides

Negatives on Plastic Film

Color negatives on plastic support See also Preservation of Traditional Color Photographic Materials

Black and white negatives on plastic support

Mechanically Printed Negatives on Paper or Plastic

Computer-generated digital-sourced print See also Digital Prints


  1. 1.0 1.1 Stulik, Dusan C. and Art Kaplan. 2013. The Atlas of Analytical Signatures of Photographic Processes. Los Angeles: The Getty Conservation Institute.

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