Hydrogel Cleans Up Sticky Paper Artifacts

An important task in conserving paper artwork is removing old glue and paste. But the wet cleaning methods traditionally used can damage fragile artwork. Hydrogels have been used to soften glues, but the hydrogel itself must then be removed. Antonio Palleschi of the University of Rome Tor Vergata, in Italy, and coworkers have now developed a rigid hydrogel infused with the starch-digesting enzyme α-amylase designed for easy removal after cleaning paper artwork (ACS Appl. Mater. Interfaces 2014, DOI: 10.1021/am504295n). The researchers started with a commercially available dextran hydrogel and loaded it with α-amylase. The hydrogel releases less water into the paper than would be required in a typical water bath. The team was able to remove the rigid gel and digested paste in a single step without needing to scrape it off, and the material left no residue on the paper. The researchers used the system to remove paste from various paper samples, including fragments from 18th- and 20th-century books.