ISO 16947:2026

Overview

ISO 16947:2026 - Natural Rubber Latex Concentrate - Determination of Zinc Oxide Stability Time (ZST) is an internationally recognized standard developed by the International Organization for Standardization (ISO). This standard specifies a detailed method for determining the zinc oxide stability time (ZST) of natural rubber latex concentrate. ZST is a key indicator of latex stability when zinc oxide is introduced, helping manufacturers and laboratories assess the quality and processability of latex products. Precise determination of ZST supports the rubber industry in maintaining high standards for raw material quality, performance, and safety.

Key Topics

• Zinc Oxide Stability Time (ZST):
  Defines the time in seconds for a latex concentrate sample to show visible flocculation after zinc oxide addition under specified conditions.
• Method Principle:
  Latex is prepared under controlled alkalinity, dilution, and temperature, then stirred at high speed with added zinc oxide until flocculation is observed.
• Sample Preparation and Test Procedure:
  Standardizes sample handling, reagent use, pH adjustment, temperature conditioning, and mechanical stirring protocols.
• Result Expression and Reporting:
  Specifies how to calculate, validate, and report the mean ZST value from duplicate determinations, ensuring result consistency.
• Precision Assessment:
  Includes guidelines for repeatability and reproducibility of the test across different laboratories, based on interlaboratory studies.

Applications

ISO 16947:2026 is essential for industries that process and manufacture natural rubber products using latex concentrate, including:

• Quality Control in Latex Production:
  Helps producers ensure that latex batches maintain desired stability when exposed to zinc oxide, reducing the risk of premature coagulation during product manufacturing.
• Product Development:
  Supports formulation design for latex gloves, medical devices, foam products, and adhesives, where latex stability is critical for performance.
• Procurement and Compliance:
  Enables buyers and suppliers to harmonize quality standards when specifying or receiving natural rubber latex concentrates.
• Research and Laboratory Analysis:
  Provides a scientific basis for comparing raw material batches, troubleshooting manufacturing issues, and validating new processing conditions or additives.
• Regulatory Compliance:
  Assists in meeting international trade and safety requirements for latex materials through standardized testing protocols.

Related Standards

For comprehensive latex quality evaluation and consistency with international best practices, consider these related ISO standards:

• ISO 35: Natural rubber latex concentrate - Determination of mechanical stability
  Procedures for assessing the mechanical stability of latex under stress.
• ISO 123: Rubber latex - Sampling
  Guidance on representative sampling methods for latex.
• ISO 124: Latex, rubber - Determination of total solids content
  Methods for quantifying the total solids within latex samples.
• ISO 976: Rubber and plastics - Polymer dispersions and rubber latices - Determination of pH
  Standardized approaches to measuring pH in latex systems.
• ISO 3310-1: Test sieves - Technical requirements and testing - Part 1: Test sieves of metal wire cloth
  Specifications for laboratory sieving apparatus used in latex testing.
• ISO 1382: Rubber - Vocabulary
  Reference for rubber and latex terminology.
• ISO 19983: Rubber - Determination of precision of test methods
  Guidance on statistical approaches for test method validation.

Adhering to ISO 16947:2026 enables natural rubber latex producers and users worldwide to consistently assess ZST, optimizing material performance and product safety across diverse applications. For further details or access to the complete standard, visit iso.org.