ISO 6588-1-2020 pdf download.Paper, board and pulps –  Determination of pH of aqueous extracts – Part 1: Cold extraction.
This document specifies a method for the determination of the pH-value defined by the electrolytes extractable by cold water from a sample of paper, hoard or pulp.
This document is applicable to all types of paper, board and pulp.
As the quantity of extractable ionic material approaches zero, as in the case of highly purified puips, the precision of the method becomes poor because of the difficulties encountered in making pH measurements on water containing little electrolytic material.
Since the extraction in this document is performed with distilled or deionised water, the pH-value measured will sometimes be different (e.g. for fully bleached pulp) from the pH-value measured under mill process conditions in which various types of process waters, e.g. chemically treated river water containing electrolytes, are used. In such cases, ISO 29681 should he used instead, as it is specifically applicable to bleached pulps from virgin fibres and to pulp samples having a low ionic strength for which the pH value will give more realistic results related to mill conditions than those obtained with this document.
For cellulosic papers used for electrical purposes, the method used should be that given in I EC 6OS54-2lJ.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 186, Paper and board — Sampling to determine average quality
ISO 7213, Pulps — Sampling for testing
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
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— IEC Electropedia: available at
4 Principle
Extraction of a sample of 2 g for 1 h with 100 ml of cold water of high purity. Filtration of the extract and addition of a salt solution. Measurement of the pH-value of the extract at a temperature between 20°C and 25 °C.ISO 6588-1 pdf download.