<p>Transparent papers have been used for centuries, though their popularity increased from the 1860s. Such papers, often held in archival collections, are associated with architectural drawings for their size, smooth surfaces, and versatility. However, these often behave differently from non-transparent paper and may be susceptible to decay beyond those associated with conventional papers. Here we present an X-ray diffraction and Fourier Transform-Infrared Spectroscopy (FT-IR) study of ten samples of historic transparent paper. Some showed a significant loss of crystallinity. FT-IR showed chemical characteristics of cellulose across all samples, alongside bands associated with diterpenoid resins such as sandarac and manila copal. This may indicate the manufacturing process to give the paper samples their transparent qualities. Together, these results can indicate the manufacturing processes used to create the transparent paper samples, the long-term condition of the cellulose which forms the main constituent of paper, and allow consideration of evidence-led conservation practices.</p>