ISO 16959:2026

Natural rubber latex concentrate — Determination of zinc oxide viscosity (ZOV)

This document specifies a method for determining the zinc oxide viscosity of natural rubber latex concentrate.

Concentré de latex de caoutchouc naturel — Détermination de la viscosité de l'oxyde de zinc (ZOV)

General Information

• Status: Published
• Publication Date: 23-Feb-2026
• ICS: 83.040.10 - Latex and raw rubber
• Technical Committee: ISO/TC 45/SC 3 - Raw materials (including latex) for use in the rubber industry
• Drafting Committee: ISO/TC 45/SC 3 - Raw materials (including latex) for use in the rubber industry
• Current Stage: 6060 - International Standard published
• Start Date: 24-Feb-2026
• Due Date: 20-Mar-2026
• Completion Date: 24-Feb-2026

Overview

ISO 16959:2026 sets out a standardized method for the determination of zinc oxide viscosity (ZOV) in natural rubber latex concentrate. Developed by the International Organization for Standardization (ISO), this standard ensures that producers and laboratories in the rubber industry can measure ZOV with accuracy and repeatability. Zinc oxide viscosity is a key indicator of latex quality and processability, impacting the performance of finished rubber products.

Key Topics

• Zinc Oxide Viscosity (ZOV): ISO 16959:2026 defines ZOV as the change in viscosity of latex concentrate when treated with zinc oxide in the presence of stabilising and gelling agents under specified test conditions.
• Test Principle: The procedure involves treating a latex sample with potassium oleate and ammonium sulphate, followed by zinc oxide, and measuring viscosity changes at set intervals.
• Required Apparatus: The method requires a Brookfield viscometer, a temperature-controlled water bath, and a pH meter. These instruments guarantee precise and consistent results.
• Sampling and Procedure: Detailed steps for sample preparation, reagent mixing, and viscosity measurement are provided, referencing related ISO standards for sampling and determination of physical properties.
• Precision and Reporting: The standard incorporates interlaboratory test results to define repeatability and reproducibility, helping users understand expected measurement variability. The test report must document method details, deviations, and sample identification.

Applications

ISO 16959:2026 is essential for:

• Natural Rubber Processing: Manufacturers utilize the ZOV method to monitor and control latex quality, ensuring suitability for downstream processing such as dipping, extrusion, and foam production.
• Product Development and Research: R&D laboratories use standardized viscosity measurements to optimize latex formulations and evaluate the impact of additives like zinc oxide.
• Quality Assurance and Compliance: Routine ZOV testing supports product certification and regulatory compliance, providing documented evidence of latex concentrate quality for both internal and external audits.
• Trade and Procurement: Buyers and sellers of latex concentrate reference ISO 16959:2026 to specify product requirements, ensuring transparency and consistency in commercial transactions.

Related Standards

ISO 16959:2026 references several important standards for materials and methods used in testing natural rubber latex:

• ISO 123: Rubber latex - Sampling
• ISO 124: Latex, rubber - Determination of total solids content
• ISO 976: Rubber and plastics - Polymer dispersions and rubber latices - Determination of pH
• ISO 1652: Rubber latex - Determination of apparent viscosity by the Brookfield test method
• ISO 1382: Rubber - Vocabulary
• ISO 19983: Rubber - Determination of precision of test methods

Adopting ISO 16959:2026 along with these related standards promotes harmonized testing practices and supports international quality benchmarks in the rubber industry.

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Keywords: ISO 16959, natural rubber latex concentrate, zinc oxide viscosity, ZOV, latex testing, rubber industry standards, latex quality, viscosity measurement, ISO standards, rubber laboratory methods.

Standards Content (Sample)

International
Standard
ISO 16959
First edition
Natural rubber latex concentrate —
2026-02
Determination of zinc oxide
viscosity (ZOV)
Concentré de latex de caoutchouc naturel — Détermination de la
viscosité de l'oxyde de zinc (ZOV)
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Sampling . 2
8 Procedure . 2
9 Expression of results . 3
10 Precision . 3
11 Test report . 3
Annex A (informative) Precision . 5
Bibliography . 7

iii
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
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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
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This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee
SC 3, Raw materials (including latex) for use in the rubber industry.
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.

iv
International Standard ISO 16959:2026(en)
Natural rubber latex concentrate — Determination of zinc
oxide viscosity (ZOV)
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all of the safety problems, if any, associated with its use. It is
the responsibility of the user to establish appropriate safety and health practices and to determine
the applicability of regulatory limitations prior to use.
1 Scope
This document specifies a method for determining the zinc oxide viscosity of natural rubber latex
concentrate.
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 123, Rubber latex — Sampling
ISO 124, Latex, rubber — Determination of total solids content
ISO 976, Rubber and plastics — Polymer dispersions and rubber latices — Determination of pH
ISO 1652, Rubber latex — Determination of apparent viscosity by the Brookfield test method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
zinc oxide viscosity
ZOV
change in viscosity of latex concentrate when treated with zinc oxide in the presence of stabilising and
gelling agents under a standard test condition
4 Principle
A test portion is treated with potassium oleate and ammonium sulphate and tested for viscosity at a
prescribed interval of time after the addition of zinc oxide.
5 Reagents
Use only reagents of recognized analytical reag
...