Determination of pH distribution through pH-related properties in deacidified model paper

Determination of the pH value of the paper is a very specific phenomenon, especially the surface pH measurement. In the case of heritage objects, such as archival documents, books, artworks on paper carriers, is a determination of real pH value in the whole structure (in cross section) of paper very important, because of the mechanism of degradation and thus the rate of degradation of the paper components at a given point in the paper structure depends on the pH value in the environment. This paper is aimed to show the possibilities of using modified papers by acid–base indicator, in the field of measurement of pH value of paper in the cross section of the paper. A calibration series of acidic samples neutralizing by magnesium bicarbonate of different concentrations was created. It was found that the indicator changed in the desired area, pH value 6–8, and it was observed gradual color change. The color parameters were measured and the most correlated parameter with pH value was found. The new method enables the observation of pH distribution in a critical cross section of modified paper after deacidification processes.