ISO 8502-6:2020

Overview

ISO 8502-6:2020 - Preparation of steel substrates before application of paints and related products - Tests for the assessment of surface cleanliness - Part 6: Extraction of water soluble contaminants for analysis (Bresle method) specifies a simple, field-capable method to extract and collect water‑soluble contaminants from steel surfaces using flexible adhesive cells (Bresle patches) or flexible sleeves. The standard is intended for pre‑painting inspection to detect salts and other water‑soluble residues that can impair coating performance.

Key topics and requirements

• Bresle method (extraction cells): Two cell types are covered - adhesive patches with a central compartment and flexible sleeves. Cells are attached to any surface shape or orientation to retain extraction water.
• Solvent: Only water is used for extraction; water shall meet at least ISO 3696 grade 3 (typically distilled or de‑ionized water, conductivity < 0.5 mS/m).
• Cell construction and sizes:
  • Standard patch compartment areas: A‑0155 (155 ±2 mm²), A‑0310 (310 ±3 mm²), A‑0625 (625 ±6 mm²), A‑1250 (1 250 ±13 mm²), A‑2500 (2 500 ±25 mm²).
  • Standard sleeve: S‑1000 (1 000 ±10 mm²).
  • Adhesive rim thickness and widths are specified (e.g., patch rim 1.5 ±0.3 mm, sleeve rim 3 ±0.3 mm).
• Apparatus: Reusable syringe (max 10 ml), needle limits (≤1 mm dia, ≤50 mm length), contact thermometer (±0.5 °C), suitable sample containers.
• Quality controls:
  • Blank tests for each batch of cells (use clean glass and same water).
  • Leak test for type testing of adhesive cells (Annex A): 12 cells tested, at least 8 must pass; testing by an accredited laboratory.
  • Report net contamination values if blank subtraction is applied.
• Procedure highlights: Select representative or high‑risk areas (pitting, welds), attach cell, inject or prefill water, agitate to dissolve salts, recover extract for analysis.
• Limitations: The extraction may give false negatives or miss contaminants in crevices, under corrosion/passivation layers, oil/grease films, or deep‑seated salts.

Applications

• Field screening for surface cleanliness before painting or coating operations.
• QA/QC during new construction, maintenance, offshore/marine, bridges, pipelines and steel fabrication.
• Determining whether cleaning/preparation methods have adequately removed water‑soluble salts that can accelerate corrosion or degrade coatings.

Who uses this standard

• Coating specifiers, inspection authorities, quality control technicians, corrosion engineers, contractors and asset owners involved in protective coating systems for steel substrates.

Related standards

• ISO 3696 - Water for analytical laboratory use (water quality).
• ISO 8502‑9 - Field method for conductometric determination of water‑soluble salts (analysis of extracts).
• ISO 8501‑1, ISO 8503‑2, ISO 8504 series - complementary standards on surface cleanliness, profile and preparation methods.

Keywords: ISO 8502‑6:2020, Bresle method, extraction of water soluble contaminants, adhesive patch, sleeve, surface cleanliness, pre‑painting inspection, field testing.