What is ISO 2431 - Flow time of paints and varnishes about?
ISO 2431 is an international standard on paints and varnishes which covers the determination of flow time by use of flow cups.
ISO 2431 specifies a method for determining the flow time of paints, varnishes and related products that can be used to control consistency.
Four flow cups of similar dimensions, but having orifice diameters of 3 mm, 4 mm, 5 mm and 6 mm, are specified. Two methods for checking the flow cups for wear and tear are given (see Annex A).
Note: Since the fabrication tolerances for such flow cups are greater than those of the flow cups specified in this document, flow time determinations with dipping flow cups give a precision which is lower than that obtained with the flow cups specified in this document (see Clause 9).
Who is ISO 2431 - Flow time of paints and varnishes for?
ISO 2431 on flow time of paints and varnishes is useful for: 
- Paints and varnishes manufacturers
Why should you use ISO 2431 - Flow time of paints and varnishes?
As is well known, many countries over the years have developed their own standard flow cups and the difficulty in correlation between them has led to considerable confusion in comparing values. The standardization of an improved design of flow cup has been recommended after careful consideration of the role of flow cups for the measurement of the flow time of paints, varnishes and related products.
Flow times are a measure for sample viscosity only for products with Newtonian or near-Newtonian flow properties. This effectively limits the practical use of flow cups. Nevertheless, for checking purposes, these flow cups do serve a useful purpose. Furthermore, the measurement of flow time is often used to confirm the application consistency.
ISO 2431 can help you with checking purposes and can be used to confirm the application consistency, which can help you in better production of your product.
What’s changed since the last update?
BS EN ISO 2431:2019 supersedes BS EN ISO 2431:2011, which is withdrawn.
BS EN ISO 2431:2019 includes some technical changes with respect to BS EN ISO 2431:2011. These are:
- A general reference to ISO 4618 has been added in Clause 3;
- The information in Clause 4 on measuring at other temperatures and humidities specified in this document has been amended;
- Figure 1 has been corrected;
- Information on conduction of measurements in a fume cupboard has been added to Clause 4.
