The Catalog provides a mean to study the history of individual paper objects. It consists from over 120.000 records of papers from pre-modern Europe found in books, archive documents, prints. The descriptions focus on the watermarks, the paper mould imprint, the objects' identity, and provide reproductions of internal paper structures. The Catalog can be searched by keywords and paper characteristics, and watermarks found by looking up a visual classification or describing their morphological components.