National foreword

This Published Document is the UK implementation of CEN ISO/TR 20659‑1:2024. It is identical to ISO/TR 20659‑1:2024. It supersedes PD ISO/TR 20659‑1:2024, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee STI/28, Paint systems for non-metallic substrates.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

This publication is not to be regarded as a British Standard.

Compliance with a Published Document cannot confer immunity from legal obligations.

This Published Document was published under the authority of the Standards Policy and Strategy Committee on 31 March 2024.

This Technical Report was approved by CEN on 6 October 2024. It has been drawn up by the Technical Committee CEN/TC 139.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and United Kingdom.

European foreword

This document (CEN ISO/TR 20659‑1:2024) has been prepared by Technical Committee ISO/TC 35 "Paints and varnishes" in collaboration with Technical Committee CEN/TC 139 “Paints and varnishes” the secretariat of which is held by DIN.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

Any feedback and questions on this document should be directed to the users’ national standards body/national committee. A complete listing of these bodies can be found on the CEN website.

Endorsement notice

The text of ISO/TR 20659‑1:2024 has been approved by CEN as CEN ISO/TR 20659‑1:2024 without any modification.

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 9, General test methods for paints and varnishes.

A list of all parts in the ISO 20659 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

1 Scope

This document gives information on an interlaboratory comparison for the determination of the yield point, using rheological test methods. The yield point is the shear stress τ below which a material does not flow.

This document provides examples of fields of applications, in which important material properties are characterized with the aid of the yield point. These fields of application include:

effectiveness of rheological additives;
shelf life (e.g. with regard to sedimentation, separation and flocculation);
stability of the structure at rest;
behaviour when starting to pump;
use in scraper systems;
wet-film thickness;
levelling and sagging behaviour (e.g. without brushmarks or sag formation);
orientation of effect pigments.

2 Normative references

3 Terms and definitions

4 Goal of the interlaboratory test

5 Metrological determination of the yield point

5.1 General

5.2 Shear rate-controlled rotational test

5.3 Yield point evaluation using flow curve regression models

5.4 Shear stress-controlled rotational test

5.5 Evaluation methods for yield points

6 Results of the comparative testing programme

6.1 Performance of the tests

6.2 Measuring samples

6.3 Method used for determination of the yield point

7 Result

8 Rheometer calibration and measurement uncertainty

Bibliography

PD CEN ISO/TR 20659-1:2024

Rheological test methods. Fundamentals and interlaboratory comparisons - Determination of the yield point

Current

Published:

31 Oct 2024