a) establishing and maintaining international optical reference transfer standards of level 2 (IR2) traceable to an international optical reference primary standard of level 1 (IR1) maintained by a standardizing laboratory;

b) distributing traceability required to achieve inter-laboratory agreement in the results of test methods specified in International Standards for optical properties of paper, board or pulp;

c) participating in the design and development of new methods and international harmonization of procedures.

When a laboratory does not undertake one or more of the activities covered by this document, such as sampling and the design/development of new methods, the requirements of those clauses do not apply.

ISO 4094:2017 is for use by specified laboratories authorized to issue optical reference transfer standards in developing their management system for quality, administrative and technical operations. Laboratory customers, regulatory authorities and accreditation bodies can also use it in confirming or recognizing the competence of laboratories.

NOTE It might be necessary to explain or interpret certain requirements in this document to ensure that the requirements are applied in a consistent manner. Guidance for consistent application can be obtained from Technical Committee ISO/TC 6.

Scope

This document specifies a method for the determination of the pH-value defined by the electrolytes extractable by hot water from a sample of paper, board or pulp.
This document is applicable to all kinds of paper, board and pulp.
As the quantity of extractable ionic material approaches zero, as in the case of highly purified pulps, 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. 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 can be 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 can be that given in IEC 60554-2[4].

This Standard prescribes the procedure to be used for making handsheets from samples of pulp for subsequent physical testing according to AS/NZS 1301.208s. Two sheet making procedures are described. One involves draining an aliquot of stock on a wire, discarding the white water and then couching, pressing and drying the formed sheet. The second, which is particularly applicable to high-yield pulps, uses the same technique except that the white water, instead of being discarded, is recirculated so that the contribution of the fines fraction is not lost.