Laser Examination as an Additional Nondestructive Method of Ink Differentiation

Twenty-two black, eight blue, and seven red inks were compared using the reflectance and luminescence mode of the Model J infrared instrument and the Laser Photonics, Inc., neodymium yttrium aluminum garnet (Nd:YAG) laser. These thirty-seven inks were compared from writing produced on Cascade Xerographic paper and Dixon Paper Company safety paper. Results indicate that, in addition to the Model J instrument and other traditional nondestructive examinations, Nd:YAG laser examination in several instances produces different results, adding another feasible link to nondestructive processes commonly used. Further, the outcome of the comparison process was affected significantly on some occasions by the type of paper on which the writing appeared.