can be wrapped with alkaline or buffered tissue paper. If the photograph has become separated from its case, a mat and backing board can be cut from alkaline buffered museum board. The mat is placed between the image and a newly cut glass plate while the backing board supports the image from behind. This "sandwich" is then sealed with Filmoplast tape. Commercial glass cleaners should not be used on new glass plates. Loose hand-coloured tintypes can be placed between mat boards. If bent, no attempt should be made to straighten them as this could cause the emulsion to crack and/or lift. Ideally, all photographic prints should be stored horizontally, although prints under 11"x14" and on stable mounts can be safely stored vertically. Prints should be stored away from light and water sources in acid-free, lignin-free boxes manufactured conforming to International Organization for Standardization (ISO) Standards 14523 (superseded in 2007 by ISO 18916) and 10214. Storage materials should pass the American National Standards Institute (ANSI) Photographic Activity Test (PAT), or similar standards, to ensure archival quality. If a photograph exhibits flaking or chipping emulsion it should not be stored in a plastic enclosure as static electricity could further damage the image. Clean cotton gloves should be worn when handling photographs to prevent skin oils and salts from damaging the surfaces. In some cases it may be necessary to contact a professional conservator. In the United States, the American Institute for Conservation of Historic and Artistic Works (AIC) provides a tool that helps identify local conservation services. In the United Kingdom and Ireland, the Conservation Register provides a similar tool that searches by specialization, business, and surname. To locate other conservation services internationally, Conservation OnLine (CoOL) Resources for Conservation Professionals provides a tool that searches by country. Colouring materials Dyes and watercolours require similar preservation measures when applied to hand-coloured photographs. Like the photographs themselves, watercolours and dyes applied by hand to photographs are susceptible to light damage and must be housed in dark storage or displayed under dim, indirect light. Common particulate pollutants can cause watercolour pigments to fade, but the paint surface can be cleaned by lightly dusting with a soft brush to remove dirt. Oil paint was often applied to tintypes, daguerreotypes, and ambrotypes. As with all photographs, the materials respond negatively to direct light sources, which can cause pigments to fade and darken, and frequent changes in relative