The Special Collections Department was founded in 1969, and collects papers, records, rare books, and other items that relate to Iowa State University, agriculture and rural life, and science and technology. As part of the Library's mission, the Department would like to increase its outreach to the public about its work. These leaflets will cover a variety of topics, and are intended to assist Iowans in preserving their history by selecting and caring for papers, photographs and other items. After being sensitized by chemicals, the plate was then exposed, and the image developed by a mercury vapor and fixed permanently by other chemicals. The extremely delicate image, which can appear as a positive or negative and can resemble a mirror when viewed, was then placed in a hinged case and covered with a brass mat and a sheet of glass.
Collodion is a form of cellulose nitrate dissolved in ether and alcohol.
The negative image produced is viewed as a positive image when the glass is backed by a dark material, such as paper, paint, or cloth. The ambrotype is usually placed in a case similar to the daguerreotype, but the image will appear as brown and milky white. The metal sheet was painted dark brown or black, exposed, developed, fixed, and then varnished. The tintype was much cheaper and more durable than the earlier photographic processes, and was very popular. It was often encased in a paper holder or album, and the image is similar in tone to the ambrotype.