SIST EN ISO 4628-10:2024 PDF

Overview

EN ISO 4628-10:2024 (ISO 4628-10:2024) is the current European/International standard for the quantitative assessment of filiform corrosion on painted or varnished surfaces. It defines a clear, reproducible method to assess the amount and size of filiform corrosion that develops from a scribed mark by measuring two parameters: the length of the longest filament (L) and the most frequent filament length (M). Pictorial examples in Annex A illustrate typical ratings but do not replace the mandatory numerical measurement methods.

Key topics and requirements

• Scope and purpose
  • Applies to coatings where filiform corrosion develops from scribed marks or damaged edges.
• Defined parameters
  • L - mean length of the longest filament (measured from left and right sides).
  • M - most frequent filament length (calculated from measurements on left/right sides or multiple zones).
• Two measurement methods
  • Method 1: For regular, symmetric corrosion - measure maximum distances left/right to obtain L and M as mean values.
  • Method 2: For irregular corrosion - measure L and multiple M values across zones and compute overall M using the specified formulae.
• Visual aids
  • Annex A provides 12 pictorial examples (L/M ratings) to help interpret severity visually; these are informative only and do not supersede numerical assessment.
• Assessment conditions
  • Perform assessments under specified illumination (see ISO 13076).
• Reporting & results
  • Results expressed compactly (e.g., filiform corrosion, L5/M3 = longest filament 5 mm, most frequent length 3 mm).
  • Test report should include coating ID, reference to ISO 4628-10:2024, surface details, illumination, whether coating was stripped, deviations, anomalies, and date.

Practical applications and users

EN ISO 4628-10:2024 is used for:

• Quality control and acceptance testing of coatings in industrial, architectural and marine applications.
• Failure analysis and root-cause investigations when coatings show under-film corrosion.
• Contract compliance and specification verification for coating suppliers and contractors.
• Research and development to quantify resistance of paint systems to filiform attack. Typical users:
• Coating manufacturers and formulators
• Corrosion engineers and inspectors
• Independent test laboratories and certification bodies
• Asset owners, specifiers, architects, and maintenance planners

Related standards

• ISO 4628-1 - general system for designating quantity/size of defects and uniform changes in appearance.
• ISO 4623-1 - definition and background on filiform corrosion (steel substrates).
• ISO 13076 - lighting and procedure for visual assessments of coatings (normative reference for illumination).

Keywords: EN ISO 4628-10:2024, ISO 4628-10, filiform corrosion assessment, paints and varnishes, coating defect evaluation, L/M rating, Method 1, Method 2, Annex A pictorial examples, test report requirements.