Modeling the "thick description" of photographs began at the intersection of personal and institutional descriptions. Comparing institutional descriptions of particular photos that were also used in personal online conversations was the initial phase. Analyzing conversations that started with a photographic image from the collection of the Library of Congress (LC) or the collection of the Manchester Historic Association (MHA) provided insights into how cultural heritage institutions could enrich the description of photographs by using informal descriptions such as those applied by Facebook users. Taking photos of family members, friends, places, and interesting objects is something people do often in their daily lives. Some photographic images are stored, and some are shared with others in gatherings, occasions, and holidays. Face-to-face conversations about remembering some of the details of photographs and the event they record are themselves rarely recorded. Digital cameras make it easy to share personal photos in Web conversations and to duplicate old photos and share them on the Internet. The World Wide Web even makes it simple to insert images from cultural heritage institutions in order to enhance conversations. Images have been used as tokens within conversations along with the sharing of information and background knowledge about them. The recorded knowledge from conversations using photographic images on Social Media (SM) has resulted in a repository of rich descriptions of photographs that often include information of a type that does not result from standard archival practices. Closed group conversations on Facebook among members of a community of interest/practice often involve the use of photographs to start conversations, convey details, and initiate story-telling about objets, events, and people. Modeling of the conversational use of photographic images on SM developed from the exploratory analyses of the historical photographic images of the Manchester, NH group on Facebook. The model was influenced by the typical model of Representation by Agency from O'Connor in O'Connor, Kearns, and Anderson Doing Things with Information: Beyond Indexing and Abstracting, by considerations of how people make and use photographs, and by the notion of functionality from Patrick Wilson's Public Knowledge, Private Ignorance: Toward a Library and Information Policy. The model offers paths for thickening the descriptions of photographs in archives and for enriching the use of photographs on social media.