Document Type


Peer Reviewed


Publication Date


DOI of Published Version


Total Pages

17 pages


Gelatin sizing was a key ingredient during the handpapermaking era. The gelatin concentration in historical papers has never been well documented, however, because measuring the gelatin content required destructive sampling. In this project we developed a non-destructive method using near infrared (NIR) spectroscopy. Gelatin concentrations of 40 historical papers from the 15th-18th centuries were determined from amino acid (AA) concentrations by using gas chromatography/mass spectroscopy. These values were combined with NIR spectra from the same papers to generate a model for predicting concentrations of unknowns. If a NIR measurement predicted a gelatin concentration in the range 0-6 percent then there is a 95% probability that the difference between the NIR model value and a destructive AA measurement would be between -1.6 and +1.3 percentage points. For 6-8 percent there is a 95% probability the difference would be between -2.0 and +1.5 percentage points, and for 8-12 percent the difference is between -3.0 and +2.0 percentage points. In a study of 159 specimens from books, loose leaves, and artworks printed from 1460-1791, the means for all papers were quite high in the 15th century and dropped an average of 20% every 50 years. Possible explanations for the decline are offered.


gelatin, sizing, paper, near infrared spectroscopy


This MS has been accepted with minor revisions for publication in e-PreservationScience, the online conservation science journal. Those revisions are in place but have not yet been approved by the editors of the journal. We will provide a link to the final published version as soon as it is available.

Journal Article Version

Submitted Manuscript Under Review


© 2011. This is the author's version of the work. Posted by permission.