TAPPI T 509 om-15测量纸张冷水提取物（未过滤）的氢离子浓度，以pH值表示。它适用于书写、打印和施胶工业用纸，但不适用于无缓冲类型，如绝缘纸和电容纸。确定的值在基本意义上可能不准确，不应根据溶液理论进行解释。根据经验，pH值与最终用途要求和纸张质量相关。这种方法避免了因受热而引起的酸碱度变化- 诱导水解。TAPPI T 435《纸提取物的氢离子浓度（pH值）（热萃取法）》中描述了热水萃取法。TAPPI T 529《纸的表面pH测量》中描述了纸的表面pH测量。

TAPPI T 509 om-15 measures the hydrogen ion concentration of a cold aqueous extract (unfiltered) of paper, expressed in terms of pH value.It is suitable for writing, printing, and sized industrial papers, but is not intended for unbuffered types such as insulating and condenser papers. The determined values may not be exact in a fundamental sense and should not be interpreted in terms of solution theory. The pH values are empirically correlated with end use requirements and paper qualities. This method avoids change of acidity or alkalinity resulting from heat-induced hydrolysis.A hot water extraction method is described in TAPPI T 435, Hydrogen Ion Concentration (pH) of Paper Extracts (Hot Extraction Method).Surface pH measurement of paper is described in TAPPI T 529, Surface pH Measurement of Paper.