Volume 38, Issue 1 (January 1993)
The pH Pen—A Means of Comparing Paper Products
Printers may use a pH pen to test the alkaline/acid content of paper stock to determine if it will be compatible with a given formulation of printing ink. Questioned-document examiners may find the pH pen useful as an additional discriminator when attempting to determine if two paper products (known and questioned) could have originated from a common source. A total of 68 different fine white paper products were compared. From a total of 2278 possible pairs (questioned and known), all but six pairs were discriminated by a combination of physical characteristics, fluorescence under UV light, and the pH pen.