Studies on the differentiation of thermal papers and estimation of the printing age of thermal paper documents

Abstract

Thermo-sensitive printers and thermo-sensitive facsimile machines are used extensively throughout China. Document examiners are often requested to confirm the authenticity of thermal paper documents. Identification of the type of thermal paper and estimation of the age of thermal paper documents could be effective methods to aid in confirming the authenticity of documents. In this paper, Fourier transform infrared (FTIR) spectrophotometry was successfully employed to differentiate between the 30 types of thermal paper. The relative age of the thermal paper documents was estimated by measuring changes in the gray value of printed strokes. The method employed resulted in curves, which indicate the relationship between the gray value of the strokes and the age of the thermal paper documents, and which are applicable for estimating the relative age of thermal paper documents in some cases. It was determined that the brand of thermal paper and thickness of strokes on the paper affected the accuracy of estimating the dates of strokes.

Keywords:

• forensic science
• document examination
• thermal paper
• relative age estimation
• gray value of strokes