Tintype

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Photographic Materials Conservation Catalog
Photographic Processes
Date: Initiated April 2011
Contributors: Amy Brost, Luisa Casella

The Photographic Materials Conservation Catalog is created and maintained by the Photographic Materials Group of the American Institute for Conservation for the convenience of the membership. The treatments, methods, or techniques described herein are provided for informational purposes. The reader assumes responsibility for any application results or interpretation of information.

Tintype


Tintype plate cross view diagram
Tintype Image courtesy: Gawain Weaver
Cross-section of tintype. Image courtesy: Mark McCormick-Goodhart
Cross-section view. Top to bottom: varnish surface with transverse scratch in view; 4micron varnish region; silver particles but undetectable collodion thickness; 40micron japanned coating; iron/ iron oxides several microns thick adhering to japan coating; iron substrate, separated from coatings and out of focus. Image courtesy: Mark McCormick-Goodhart
Cased tintype with image layer detached from metal support

Historical Facts
Invented: The tintype (also referred to as Ferrotype or Melainotype) was patented by Hamilton Smith in 1856 in the United States.
Main Period of Use: Throughout the 19th century.Very popular with street photographers, particularly during the American Civil War.
Historic Practioners: The process was commonly used by portraitists and street photographers.
Contemporary Practitioners: Robb Kendrick; Scully Osterman

Identification Characteristics
Image layer: Highlights are collodion and physically developed silver. Shadows are the varnished support. Tintypes commonly show low contrast.
Color: Monochrome (may have applied color).
Support: Tin metal plate.
Analysis: Earlier tintypes may be housed in cases, similar to that of an ambrotype or daguerreotype. In these cases, to distinguish from an ambrotype a magnet may be used for a quick identification of the support. Later tintypes were commonly pasted onto paper cards, often surrounded by decorative borders. The plate was attached with gummed paper that was attached to the back of the plate and the paper window mat. Tintypes were also commonly mounted onto albums or jewelry (buttons, earrings, etc.).

Process Overview
The tin plate must be wet for the whole procedure - sensitizing, exposing, developing, fixing, and rinsing. Collodion is poured to the center of the plate and allowed to flow to cover the whole plate. Surface tension and a steady hand keep it from spilling. Once it sets up somewhat, the plate is taken into a dark room and placed into a bath of silver nitrate, which sensitizes it. Then the plate is placed into a plate holder (a back for a large format camera). Then the plate is placed in the camera and exposed. It is only sensitive to blue/UV light, so artificial blue-light sources are helpful, and sunlight is effective. Because the exposed surface of the plate is also the final image, the result is a reverse image. The camera back is taken into the darkroom and a shot-glass of developer is poured onto the surface and must be poured evenly or defects result. After about 30 seconds, the plate is rinsed. It is fixed in hypo or potassium cyanide to dissolve the remaining unexposed silver salts. After the plate is dry (sometimes dried over heat), varnish is poured on to protect the image.

Conservation and Treatment

  • Metal support is thin and flexible and prone to bending or deformation.
  • Support commonly suffers corrosion due to exposure to water or high humidity in areas where the varnish has crazing or scratching.
  • Image layer is typically in good condition due to protection from oxidation by the varnish.
  • Varnish may present discoloration, crazing or cracking.
  • Conservation treatment is commonly restricted to surface dust removal using soft brush and air bulb.
  • Mechanical removal of corrosion products under magnification using small tools may be successful but great care must be taken as corrosion is often spread through the plate underneath the very fragile image layer that can inadvertently be displaced during this treatment.
  • Commercial rust removers are too acidic and may attach the iron metal, varnishes, collodion and silver image. Promising results were found in research into the use of tannic acid in stabilizing rusted supports and preventing further corrosion (Chen et. al. 2000).
  • Consolidation of flaking image layers can be attempted using acryloid B-72 or polyvinyl acetate resins in ethanol(Kashina, 2003). This treatment is problematic because it must take into account that ethanol may dissolve the image layer. In addition, highly corroded supports will further complicate consolidation.
  • Compensation of loss has been carried out suing toned gelatin fills (Chen et. al. 2000) or microcrystalline wax and pigments (Kashina, 2003).
  • Bent supports may be reduced on plates with sturdy/ non flaking image layer by carefully placing the object face down over a smooth surface (such as Mylar or smooth Tyvek) and gently applying pressure or burnishing the bend with a Teflon spatula.
  • Varnish removal should not be attempted as the solubility characteristics of these and that of the collodion are similar. In addition, the physically developed silver of the plates is often found on the surface of the collodion layer (McCormick-Goodhart, 1990) that would be removed or displaced by varnish removal.

See also ambrotype conservation and treatment and cased photographs chapter.

Housing and Storage

  • Tintypes should be stored in low humidity environments to prevent corrosion (below 50% RH); however, if plates are in original case composed of paper, leather and/or wood, humidity should not be lower than 30%.
  • Loose tintypes may be housed in four-flap PAT tested paper enclosures or custom-made window-mats. They may also be housed in polyester sleeves if the image layer is sturdy and not flaking.


Emergency Recovery

  • Tintypes are particularly damaged by water or high humidity. In the event of water emergency, plates should be air dried. Wet collodion processes should not be freeze dried (Hendriks and Lesser, 1983).



RESOURCES
Conservation


Process and Historic Material

  • Burns. Stanley B.. 1995. "Forgotten Marriage, the Painted Tintype & The Decorative Frame, 1860-1910: A Lost Chapter in American Portraiture". Burns Press: New York.
  • Luminous-Lint entry on Tintypes: http://www.luminous-lint.com/app/contents/the/690/
  • Rinhart, Floyd. 1999. "The American Tintype". Ohio State University Press: Columbus Ohio.


Contemporary Practice


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