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TAPPI
T 435 om-22
Hydrogen ion concentration (pH) of paper extracts (hot extraction method)
2022
5
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This method measures the hydrogen ion concentration, expressed in terms of pH, of an aqueous extract
of paper obtained by hot extraction (unfiltered and extracted by boiling water for one hour). It may be applied to writing, printing and sized industrial paper, but it is not intended for unbuffered
types such as electrical insulating and condenser papers. Values determined by this method will reflect changes
resulting from heat-induced hydrolysis. Additives, such as those used in filled and coated papers can have an effect
on the extract pH. ....