2.6 Photographs and film

Photographs and film revolutionized visual documentation, preserving moments in time. From early daguerreotypes to modern digital images, these mediums have evolved, each with unique characteristics and preservation challenges. Understanding their composition and structure is crucial for conservators.

Conservation of photographs and film involves addressing chemical, environmental, and physical deterioration. Techniques range from preventive measures like climate control to active treatments such as cleaning and stabilization. Ethical considerations guide conservation efforts, balancing preservation with accessibility.

Photographic Processes and Characteristics

Early Photographic Techniques

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  Daguerreotype of Laura Haddrick, 1867 | B 70149 Portrait, ta… | Flickr View original

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  NMA.0052882_01 | Portrait of an unknown woman. Daguerreotype… | Flickr View original

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  NMA.0051874_01 | Group portrait. Daguerreotype, photographer… | Flickr View original

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Top images from around the web for Early Photographic Techniques

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  NMA.0051874_01 | Group portrait. Daguerreotype, photographer… | Flickr View original

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  Daguerreotype of Laura Haddrick, 1867 | B 70149 Portrait, ta… | Flickr View original

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  NMA.0052882_01 | Portrait of an unknown woman. Daguerreotype… | Flickr View original

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  NMA.0051874_01 | Group portrait. Daguerreotype, photographer… | Flickr View original

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  Daguerreotype of Laura Haddrick, 1867 | B 70149 Portrait, ta… | Flickr View original

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• Daguerreotype process creates a direct positive image on a silver-plated copper sheet resulting in a unique, mirror-like image
• Albumen prints feature glossy surfaces and warm tones using egg white as a binder for light-sensitive silver salts
• Gelatin silver prints emerged as the most common black and white photographic process of the 20th century using gelatin as a binder for light-sensitive silver halides
  • Produced sharp, high-contrast images
  • Allowed for mass production of photographs

Modern Photographic Innovations

• Chromogenic color prints create dye images through chemical reactions during development resulting in vibrant, multi-layered color photographs
  • Introduced in the 1930s with Kodachrome film
  • Became the dominant color photography process for decades
• Instant photography popularized by Polaroid uses self-developing film to produce a finished print shortly after exposure
  • Eliminated the need for separate developing and printing processes
  • Allowed for immediate review and sharing of images
• Digital photography captures images using electronic sensors storing them as digital files rather than on physical film
  • Revolutionized the photography industry in the late 20th century
  • Offers advantages like instant review, easy editing, and storage of large numbers of images

Composition and Structure of Photographic Materials

Emulsion and Support Materials

• Photographic emulsions consist of light-sensitive silver halides suspended in a gelatin binder coated onto a support material
  • Silver halides (silver chloride, silver bromide, silver iodide) form the basis of the light-sensitive layer
  • Gelatin acts as a protective colloid and allows for even dispersion of silver halides
• Support materials for photographs vary based on the process and time period
  • Metal (daguerreotypes)
  • Glass (ambrotypes, negatives)
  • Paper (prints)
  • Plastic (film negatives, transparencies)
• Photographic papers often have a baryta layer composed of barium sulfate and gelatin
  • Provides a smooth surface for the emulsion
  • Enhances image quality by increasing reflectivity and whiteness

Color Photography and Film Base Evolution

• Color photographs contain multiple layers of light-sensitive emulsions each responsive to different wavelengths of light
  • Typically include cyan, magenta, and yellow dye-forming layers
  • Produce a full-color image through subtractive color mixing
• Photographic film base materials evolved over time to improve stability and safety
  • Cellulose nitrate (highly flammable, used until the 1950s)
  • Cellulose acetate ("safety film", prone to vinegar syndrome)
  • Polyester (most stable, used in modern films)
• Toning processes alter the chemical composition of silver image particles
  • Gold toning (increases warmth and improves stability)
  • Selenium toning (increases contrast and enhances longevity)

Deterioration Issues in Photographs and Films

Chemical and Environmental Degradation

• Silver mirroring creates a bluish metallic sheen on the surface of silver-based photographs
  • Results from migration and oxidation of silver particles
  • Often seen in the shadow areas of images
• Fading and color shifts in chromogenic prints occur due to the inherent instability of organic dyes
  • Cyan dyes typically fade faster than magenta and yellow
  • Can lead to overall color balance changes or loss of image detail
• Cellulose nitrate and cellulose acetate films undergo chemical degradation
  • Causes shrinkage, brittleness, and release of acidic gases (vinegar syndrome)
  • Can lead to complete loss of image if left untreated
• Gelatin binders in photographic materials become susceptible to mold growth in high humidity environments
  • Causes irreversible damage to the image
  • Can spread to other materials in storage

Physical Damage and Light-Induced Deterioration

• Physical damage occurs due to improper handling or storage of photographic materials
  • Tears, creases, and abrasions
  • Fingerprints and surface dirt
  • Insect damage or rodent infestation
• Light-induced fading affects both color and black and white photographs
  • Ultraviolet radiation particularly harmful to image stability
  • Can cause color shifts, loss of contrast, and overall image fading
  • Cumulative and irreversible process

Conservation Techniques for Photographs and Films

Preventive Conservation Measures

• Environmental control crucial for slowing chemical deterioration processes in photographic materials
  • Temperature regulation (generally cooler temperatures preferred)
  • Humidity control (typically 30-40% RH for most materials)
  • Air filtration to remove pollutants and particulates
• Proper storage materials protect photographs and films from physical damage and chemical interactions
  • Acid-free enclosures (sleeves, folders)
  • Archival-quality boxes (lignin-free, buffered)
  • Use of inert plastics (polyester, polypropylene) for certain materials
• Digital preservation techniques aid in preserving image content for future access
  • High-resolution scanning creates digital surrogates
  • Metadata documentation ensures proper identification and context
  • Regular migration and backup of digital files

Treatment and Stabilization Methods

• Cleaning techniques for photographs vary based on the process
  • Gentle brush cleaning for surface dirt
  • Use of solvents for adhesive removal
  • Specialized methods like light ablation for stubborn contaminants
• Stabilization of deteriorating film bases involves various approaches
  • Duplication onto more stable supports (film-to-film copying)
  • Cold storage to slow chemical degradation (especially for color materials)
  • Encapsulation in inert materials for severely degraded items
• Consolidation and repair techniques address damaged photographs
  • Use of appropriate adhesives (wheat starch paste, methyl cellulose)
  • Application of backing materials for structural support
  • Mending tears with Japanese tissue or heat-set tissue
• Ethical considerations in photograph conservation emphasize minimal intervention
  • Reversibility of treatments preserves material's authenticity
  • Documentation of all conservation actions taken
  • Balance between preservation and access needs