EVS-EN ISO 8501-3:2025

The performance of protective coatings of paint and related products applied to steel is significantly affected by the state of the steel surface immediately prior to painting. ISO 8501-3 provides requirements for steel building organisations to avoid unnecessary production costs for steel structures that will be painted.

ISO 8501-3 provides requirements to identify visible imperfections and defines three preparation grades for welds, edges and surfaces of steel to assist in achieving efficient corrosion protection. Such imperfections can be visible before or can become visible after an abrasive blast cleaning process.

The principal factors that are known to influence the performance of protective coatings of paints and related products applied to steel are:

a) the presence of rust and mill scale
b) the presence of surface contaminants, including salts, dust, oils and greases
c) the surface profile.

Although ISO 8501-3 has been developed specifically for preparation of steel, the defined preparation grades will generally be appropriate when preparing other metal surfaces e.g. aluminium, castings, if agreed.

ISO 8501-3:2025 text has been approved in Europe as EN ISO 8501-3:2025 without any changes.