The alkaline reserve is determined according to ISO 10716. The acid-related degradation of paper and cardboard is a challenge for archives and libraries because acidic substances such as aluminum sulfate were added in the past during paper production. To counteract this, these papers are "deacidified". Calcium carbonate or magnesium carbonate, for example, is added to neutralize the acids in the paper and additionally provide an alkaline reserve against further acid formation.
Therefore, this method is used to determine the content of alkaline pigments or other alkaline materials in paper and board.