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Home , Blueprint, Cyanotype

ConserveO Gram July 1995 Number 19/9

Caring For And

The bright blue or process unframed with other photographic prints. was developed in 1842. It was first used to When blueprints or cyanotypes are made without record herbarium specimens without benefit of a they may also be labeled as photo­ . The specimens were placed directly grams. These cameraless images are most against sheets of paper impregnated with commonly a ghostly white reproduction of plant chemicals and exposed to light. These specimens or objects on a brilliant blue cameraless images were most common between background-a reverse image of most 1842 and 1860, although some later artists and cyanotypes- housed with or scientists also produced them. scientific illustrations.

Between 1880 and the 1920s the process became Both blueprints and cyanotypes are produced popular for producing prints from photographic using light-sensitive iron salts that lodge deep in negatives called cyanotypes ( means blue). the uncoated paper. The paper fibers of The most common use of the process occurred blueprints and cyanotypes are visible under between 1890 and the present, when it was used 30-power magnification. Due to their acidic for producing copies of architectural and nature, cyanotypes and blueprints are frequently engineering drawings, called blueprints. Many brittle and may have some brown staining, or architects of the last hundred years used foxing, that results from mold growth around blueprints to reproduce their working drawings, minute metal particles in the paper. Despite and many amateur and professional these problems, blueprint and cyanotype images photographers used cyanotypes to produce draft are usually stable and can maintain a surprisingly copies of photographic prints. bright image.

Appearance and Deterioration Blueprint and cyanotype images commonly fade when: Both blueprints and cyanotypes have bright blue image detail with white highlights on smooth • placed in an alkaline (buffered) environment. matte-surfaced uncoated paper. However, if the An alkaline or buffered environment causes images were photographically reversed, they blueprints and cyanotypes to lose image detail may have white image detail with blue and density. The images first turn yellowish­ highlights. These reversed images are brown before eventually fading to white. sometimes labeled with their alternative names ferroprussiate prints or pellet process prints or • exposed to light. Original blueprints and the technical process name . cyanotypes should not be used in exhibitions.

Blueprints most often reproduce architectural or NOTE: Surprisingly, images that have faded or engineering drawings, , and plans. lost image detail due to light can They are often discovered in construction files, recover image density over time if they are oversized cases, and maintenance records. stored in the dark in a neutral, non-buffered Cyanotypes are photographs usually housed environment. National Park Service Conserve O Gram 19/9

Housing Blueprints and Cyanotypes plastic sleeves or folders, including polyester. Polyester sleeves or folders are recommended Since blueprints and cyanotypes can be damaged only if the cyanotype or blueprint is not brittle by both light and an alkaline environment, but is experiencing fading due to contact with blueprints and oversize cyanotypes should be buffered or alkaline materials from which it housed.flat in unbuffered, neutral-pH folders, cannot otherwise readily be separated. within metal map cases or within shallow solander-type unbuffered boxes. Cyanotypes that Handling are 8" x 10" or less may be housed upright on their edge within an unbuffered, neutral-pH four­ All folders within a drawer or box should be the flap sleeve, then in an unbuffered folder, and same size, regardless of the size of the blueprint finally in boxes like other photographs. Use or cyanotype in them. This procedure will keep unbuffered folder stock that is high alpha smaller folders from shifting to the back of the cellulose and low-lignin. map case or box and getting lost or crammed together. Each folder should be carefully Because of their brittleness, blueprints and labelled near its fold in pencil with the collection cyanotypes tear easily. Each blueprint or name, box or drawer number, accession/catalog cyanotype should be housed in its own individual number, other identifying number, photographer folder that is unbuffered, high alpha cellulose, or artist, subject, date, and any restrictions­ and Iow-lignin. If, for reasons of economy, this particularly those related to fragility. is not possible, use unbuffered neutral-pH tissue paper to separate individual images from each Since blueprints and cyanotypes lack mechanical other and from their folder. Never use strength, they must not be bent, folded, rolled, buffered, glassine, or ground wood housing or moved without a rigid support. Therefore, materials. Avoid placing more than three researchers and staff must remove a folder oversize items in a folder because of their completely from a map case drawer or box fragility. Rolling blueprints or cyanotypes on before opening the folder to view an item. tubes is discouraged because of their brittleness When removing a single folder from a drawer or and lack of durability. If rolled they tend to box, support the folder with a piece of acid-free crack and tear. unbuffered board.

If blueprints to be rehoused are already rolled or Riffling through folders in a map case or box by folded you must flatten and unfold them only if bending the folders back upon each other can they are strong and durable. Brittle or fragile also damage the images. Consider storing items should be flattened or unfolded by a folders in a map case with their labeled spines conservator. (See Conserve O Gram 13/2, How (i.e., the fold portion of the folder) facing the to Flatten Folded or Rolled Paper Documents.) drawer front to discourage browsing. All staff should be warned not to fold or bend these Plastic Sleeves and Encapsulation images towards the back of the drawer to speed browsing. Instead, remove the images from the Placing the highly acidic blueprints and drawer in their folders. cyanotype images in a microenvironment that traps the acid next to the paper enhances the Researchers and staff who work with oversize paper's brittleness. However, polyester sleeves blueprints and cyanotypes require a large clear do have the advantage of limiting contact with an work space. The must be big enough to alkaline environment, thus discouraging image allow three stacks of folders as well as a writing fading. Generally avoid encapsulating brittle surface: one stack contains the folders already blueprints or cyanotypes or housing them in any viewed; a second stack contains the folders to

Caringfor Blueprints and Cyanotypes Conserve O Gram 19/9 National Park Service

be viewed; and the third stack is the folders References being viewed. Coe, Brian and Mark Haworth-Booth. A Guide Blueprints or cyanotypes that have original to Early Photographic Processes. London: notations or changes by the image creator or the Victoria and Albert Museum, 1983. image creator's staff are commonly treated as original records. Such original notations on Reilly, James M. Care and Identification of blueprints are relatively common with working 19th Century Photographic Prints. Rochester, drawings. Many blueprints or cyanotypes have NY: Eastman Kodak Publication No. G-2s, outlasted the original or drawing upon 1986. which they are based, making them the last record of an image. Last surviving copies Ritzenthaler, Mary Lynn, Gerald J. Munoff, should be treated as originals. Margery S. Long. Archives and Manuscripts: Administration of Photographic Collections. Sources SAA Basic Manual Series. Chicago: Society of American Archivists, 1984. Unbuffered, pH-neutral folders and folder stock; storage boxes and solander-type boxes; and Wilhelm, Henry. The Permanence and Care of unbuffered, pH-neutral tissue paper are available Photographs: Traditional and Digital from archival-quality materials suppliers, such as Color Prints, Color Negatives, Slides, and the following: Motion Pictures. Grinnell, Iowa: Preservation Publishing Company, 1993. Conservation Resources International, 8000-H Forbes Place, Springfield, VA 22151; (800) 634--6932 or (703) 321-7730; Fax (703) 321-0629.

Light Impressions Corporation, 439 Monroe Avenue, P.O. Box 940, Rochester, NY 14603- 0940; (800) 828--6216 or (716) 271-8960; Fax (716) 442-7318. Diane Vogt-O'Connor Archivist University Products, 517 Main Street, P.O. Box Curatorial Services Division 101, Holyoke, MA 01041-0101; (800) 628-1912 National Park Service or (413) 532-9431; Fax (800) 532-9281. Washington, DC 20013-7127

The Conserve O Gram series is published as a reference on The series is distributed to all NPS units and is available to non-NPS collections management and curatorial issues. Mention of a product, institutions and interested individuals by subscription through the a manufacturer, or a supplier by name in this publication does not Superintendent of Documents, U.S. Government Office, constitute an endorsement of that product or supplier by the National Washington, 0.C. 20402, FAX (202) 512-2233. For further Park Service. Sources named are not all inclusive. It is suggested infonnation and guidance concerning any of the topics or proc edures that readers also seek alternative product and vendor infonnation in addressed in the series, contact the NPS Curatorial Services Division , order to assess the full range of available supplies and equipment. P.O. Box 37127, Washington, DC 20013-7127 ; (202) 343-8142. Caringfor Blueprints and Cyanotype 3