Identify Those Fibers

NIST researchers, in collaboration with the U.S. Government Publishing Office, have developed a novel, nondestructive method to rapidly measure the wood and non-wood fiber components in paper.

Identifying and measuring the ratio of plant fibers used to manufacture paper has wide application in criminal forensics, conserving art, authenticating historical documents, assessing the content of recycled paper and ensuring that passports and other U.S. government documents are printed on the requisite security paper.

For example, high-quality government documents are often created with non-wood fibers such as cotton. Wood-derived fibers make paper more brittle over time and can help reveal its age. Forensic investigators at a crime scene often look for the transfer of materials between individuals; such materials include the kinds of fibers that are in paper.

Despite its importance, the current method of analyzing paper has changed little since fiber technologist Mary Rollins of NIST (then known as the National Bureau of Standards) helped pioneer the method in the 1920s and 30s. By modern standards, however, the technique is laborious, time-consuming and highly subjective. The process also requires sacrificing a portion of the paper sample, which may be limited and needed for evidence.

The new technique, known as dielectric spectroscopy, identifies the composition of materials by examining how particular molecules reorient themselves in response to a rapidly changing electric field. The paper sample remains intact.

The team, along with other scientists, is now exploring how the same method might be used to detect harmful bacteria on surfaces in hospital rooms, and on recently caught fish and other perishable foods.