ISO 787-13:2019

Overview

ISO 787-13:2019 defines standardized test methods for determining the content of water-soluble sulphates, chlorides, and nitrates in pigments and extenders. Published by the International Organization for Standardization (ISO), this third edition updates procedures essential for quality control, compliance, and material characterization within the pigments industry. The document helps laboratories apply uniform analytical techniques to assess soluble ionic impurities, which can impact pigment performance and stability in various applications.

Key Topics

• Scope and Purpose
  Specifies the determination of water-soluble sulphates, chlorides, and nitrates in pigments through standardized extraction and quantification techniques.

• Test Procedures

  • Water-soluble Sulphates: Hot or cold aqueous extract acidified and reacted with barium chloride to precipitate barium sulphate; weighed after filtering and ignition.
  • Water-soluble Chlorides: Titration of the aqueous extract with silver nitrate in presence of potassium chromate as an indicator, monitoring a color change to detect chloride content.
  • Water-soluble Nitrates: Reduction of nitrates in the aqueous extract via Devarda’s alloy and sodium hydroxide, followed by distillation and colorimetric analysis using Nessler's reagent.

• Sampling and Preparation
  Sampling aligned with ISO 15528 ensures representative pigment samples; hot or cold extraction techniques determine the soluble fraction.

• Reagents and Apparatus
  Use of high-purity analytical reagents, including hydrochloric acid, silver nitrate, barium chloride, potassium chromate, sodium hydroxide, Devarda’s alloy, and Nessler's reagent, alongside standard laboratory apparatus such as sintered-silica crucibles and distillation setups.

• Expression of Results
  Precise calculation formulas convert measured values into percentage mass fractions of sulphates, chlorides, and nitrates present in the pigment samples, ensuring consistent and comparable reporting.

Applications

• Quality Control in Pigment Manufacturing
  Enables manufacturers to monitor and control levels of water-soluble ionic contaminants that may affect pigment purity, color fastness, and compatibility in applications such as paints, coatings, plastics, and inks.

• Compliance with Industry Standards
  Assists pigment producers and users in adhering to regulatory and customer specifications regarding soluble salt content, reducing risks related to adverse chemical reactions or product instability.

• Research and Development
  Facilitates pigment formulation optimization by providing reliable data on soluble impurities that influence pigment processing and end-use performance.

• Environmental and Safety Assessments
  Measuring soluble sulphates, chlorides, and nitrates supports evaluation of disposal and environmental impacts of pigment materials.

Related Standards

• ISO 15528 – Sampling procedures for paints, varnishes, and raw materials, pertinent for obtaining representative pigment samples before testing.

• ISO 787-3 – General methods for determining matter soluble in water by hot extraction, referenced for extraction procedure.

• ISO 787-8 – Methods for determining matter soluble in water by cold extraction, alternative extraction method specified.

• ISO 18451-1 – Terminology for pigments, dyestuffs, and extenders, providing standardized definitions used throughout the test methods.

This suite of ISO standards ensures comprehensive, harmonized approaches to pigment testing, enhancing testing accuracy and data comparability across laboratories worldwide.

Keywords: ISO 787-13, pigments test methods, water-soluble sulphates, water-soluble chlorides, water-soluble nitrates, pigment quality control, pigment impurities analysis, standardized pigment testing, pigment extraction, pigment contaminants analysis