May also be stored horizontally (flat), especially larger or fragmented slides. Storage Orientation Store vertically with dividers between each slide. All storage materials should pass the Photographic Activity Test (PAT) as specified in ISO Standard 18916:2007. Such seams (if any) should be on the sides of the enclosure, not down its center. If stored in a paper enclosure, position photo emulsion side away from seams. Delaminating emulsions can be protected under a plate of glass. Broken, flaking or delaminating plates should be stored flat in a sink mat (or other enclosure to contain fragments) also made from archival paper. Glass slides in good condition are best stored in a four-flap enclosure made from archival-quality paper sleeves and envelopes are acceptable. Each slide should have its own enclosure to protect it from dust, handling damage, and changes in environmental conditions. Storage Enclosure(s) Acid-free enclosures and/or folders are strongly advised. Storage EnvironmentĬool storage (below 50 degrees) is recommended, though cold storage should be avoided for glass based images.Allowable Fluctuation: ±5☏ ±5% RH Black-and-white glass slides were phased out by color transparencies on film, which became increasingly available after World War II. After 1890, glass slides were commonly made from commercially available gelatin silver plates. Collodion was also used in the early forms. Most glass slides produced before the 1880s were made with albumen. Stereograph slides were a popular parlor amusement and often featured topographical views. Lantern slides were used for home entertainment and as illustration in education settings. They were developed from glass negatives to produce a positive image that could be viewed using a magic lantern or stereoscopic viewer. Common Size(s) Lantern slide: 3¼" × 4" 3¼" × 3¼" 3½" × 3¼" Stereograph slide: 3½" × 7" Background B&W slides on glass were produced from 1850 to the 1950s, but their use persisted for decades thereafter. Regardless of the binder, care should be taken to maintain stable relative humidity so to prevent weakening of the emulsion. Collodion is more stable than gelatin but is susceptible to image-eliminating abrasion. Gelatin emulsions on glass are known to flake and delaminate due to factors both manageable (environmental) and not (manufacture). As with all glass plates, these slides are delicate and can be severely damaged through cracking and breakage. Gelatin slides are prone to delamination of the image layer. Acidic environments and enclosures spur these forms of oxidative deterioration along. Without glass cover, the slide is at a higher risk of delamination, flaking, fading, yellowing, and silver mirroring. Composition Supportĭeterioration Since most glass slides are protected by a glass cover, they are often in decent condition, despite having the same elemental instability of either a silver gelatin, collodion, or albumen negative on glass. Hand-colored images can be identified by their saturated, unnaturally bold colors, and sometimes selective coloring. Hand-coloring was an additive color method: the manual application of water colors, paints, or aniline dyes to the image surface. Many B&W slides were "color-enhanced," making them appear at first glance to be color slides. Glass slides may be hand-colored, tinted, or toned. Stereograph slides are rectangular and feature two nearly identical images side-by-side in contrast, lantern slides vary in size but are often nearly square and contain one image. Stereograph slides were given a glass cover only if they were made with an albumen binder. Lantern slides often have a glass cover in addition to its glass support, and they are sealed along the edges with strips of black tape. A glass slide will likely be a positive image, which sets it apart from a glass plate negative. 1960 Image Tone Monochrome (gray-black, warm brown, ocher orange to olive green ) hand-coloring or tinting possible Description A black-and-white glass slide is comprised of a thin glass support with an albumen, collodion, or gelatin binder, and a silver image. Although slides will often be discovered in a cardboard container like this, it is inadvisable for long-term storage.ĭates 1850 – c. Courtesy of Landscape Architecture, UIUC, University of Illinois Board of Trustees. Courtesy of Landscape Architecture, UIUC, University of Illinois Board of Trustees.īroken slide held in place by black tape seal.
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