pH Measurement of Paper

Electrochemical measurement of pH on paper artifacts is a very important tool to assess the state of paper conservation. It is necessary to measure paper pH, because it is one of the most important parameters defining its longevity. Different methods using different types of electrodes have been standardized to provide reproducible pH values of paper.

pH measurement of paper extracts

TAPPI T 509“Hydrogen Ion Concentration (pH) of Paper Extracts - Cold Extraction Method”

TAPPI T 435“Hydrogen Ion Concentration (pH) of Paper Extracts - Hot Extraction Method”

ISO 6588-1 Paper, board and pulps — Determination of pH of aqueous extracts — Part 1: Cold extraction

ISO 6588-2 Paper, board and pulps — Determination of pH of aqueous extracts — Part 2: Hot extraction

In these methods，the paper, board or pulp are extractable by hot or cold distilled or deionised water. Measurement of the pH-value of the extract at a temperature between 20 °C and 25 °C.

The pH has been measured by pH meter with spherical glass electrode.

Surface pH measurement of paper

TAPPI/ANSI T 529 om-21“Surface pH measurement of paper“

This non-destructive test may be used to measure the hydrogen ion concentration (pH) on the surface of the paper in books and documents that constitute the collections of libraries and government archives.  
pH values obtained through the application of this method to sized materials such as writing, printing, and industrial papers reflect only the pH of the surface of these materials and should not be construed as pH values which may be determined by the cold water extraction method of the same material . 

The pH has been measured by pH meter with a surface glass electrode.