SIST EN ISO 2431:2019 PDF

Overview

EN ISO 2431:2019 - Paints and varnishes: Determination of flow time by use of flow cups (ISO 2431:2019) is a CEN-endorsed international standard that defines a reproducible method to measure the flow time of paints, varnishes and related products for consistency control. The standard specifies a set of four standardized flow cups (orifice diameters 3 mm, 4 mm, 5 mm and 6 mm) and the procedures, checks and conditions required to obtain reliable flow-time data.

Key topics and requirements

• Scope and limitations
  • Method is applicable only to materials for which the breakpoint of flow from the cup orifice can be determined reliably (primarily Newtonian or near-Newtonian materials).
  • The standard notes practical limitations for materials with flow times near the upper measurement limit (≈100 s) where breakpoint determination becomes difficult.
• Flow cups and apparatus
  • Four specified cups with close fabrication tolerances and defined dimensions; orifice sizes: 3 mm, 4 mm, 5 mm, 6 mm.
  • Replaceable-jet flow cups and commonly used dipping flow cups are excluded because they do not meet the tight tolerances required for this method.
• Procedure essentials
  • Preliminary check for Newtonian flow behavior, temperature control/adjustment, cup preparation, filling and timing of flow, and repeat determinations for consistency.
  • Two methods to check flow cups for wear and tear are provided (see Annex A).
• Precision and reporting
  • The document gives guidance on repeatability and reproducibility and specifies required elements for the test report.

Practical applications and users

• Quality control teams in paint, varnish and coatings manufacturing use EN ISO 2431:2019 for routine consistency control and production acceptance testing.
• Laboratories and QC analysts use the flow-time method as a fast screening test for viscosity-related properties when Newtonian flow conditions apply.
• Formulation scientists may use results to monitor batch-to-batch variation or to confirm application consistency (spray, brush, roller).
• Note: for non-Newtonian or strongly thixotropic products, alternative viscometric methods (e.g., rotational viscometers) are recommended.

Related standards

• ISO 3219 - rotational viscometry (recommended for non-Newtonian products)
• ISO 4618 - general terminology for paints and varnishes (referenced)
• EN ISO 2431:2011 - previous edition (superseded by 2019)

EN ISO 2431:2019 is essential for standardized, reproducible flow cup testing and should be consulted directly for full procedural details, annex checks, and precision data.