Cold Extraction pH Test

IPI tests paper-based materials and adhesives for pH levels using a modification (described in ISO 18902) of the standardized test, TAPPI T 509 Hydrogen Ion Concentration (pH) of Paper Extracts (Cold Extraction Method). This determines if a material is acidic, basic, or neutral. The acidity of a material is described by its pH value. The pH scale ranges from 0 to 14, where 7 is neutral, below 7 is acidic, and above 7 is alkaline. Acidic environments can accelerate the degradation of paper and plastic supports making them brittle. Highly alkaline environments, on the other hand, can also cause decay, such as weakening of a gelatin binder. Since an upper pH limit is just as important as a lower pH limit, the standard incorporates an upper pH limit of 10. To be considered photo-safe, paper-based materials and adhesives must have a pH equal to or greater than the reference water used in testing and less than 10 when measured by a cold extraction pH method.