ISO 12944-6:2018

Overview

ISO 12944-6:2018 - Paints and varnishes: Corrosion protection of steel structures by protective paint systems - Part 6 specifies laboratory performance test methods used to assess paint systems for the corrosion protection of carbon steel structures. The standard defines how artificial ageing tests (salt spray, condensation, cyclic ageing, etc.) are to be performed and interpreted as an aid in selecting suitable protective paint systems, not as an exact prediction of in-service durability.

Key points:

• Applies to paint systems on uncoated carbon steel, hot dip galvanized steel (ISO 1461), and thermal‑sprayed metallic coatings (ISO 2063‑1 / ISO 2063‑2).
• Excludes electroplated or previously painted steel.
• Considers corrosivity categories C2 to C5 and Im1 to Im3 per ISO 12944‑2.

Key Topics and Requirements

• Test scope and purpose: Laboratory artificial‑ageing procedures designed to accelerate degradation and evaluate resistance to moisture, salt fog and other stressors relevant to corrosion protection.
• Test panels and preparation: Requirements for substrate types (carbon steel, hot dip galvanized, thermal‑sprayed), sampling of paints, number of panels, and maximum film thickness limits for systems under test.
• Test procedures: Includes salt spray (ISO 9227), condensation/humidity (ISO 6270-1), and a normative cyclic ageing test (Annex B) increasingly used for severe categories (C4/C5). Test durations and regimes are specified for different corrosivity categories (see standard for tables).
• Assessment criteria: Evaluation before and after artificial ageing using standardized methods for blistering, rusting, cracking, flaking and delamination (ISO 4628 series), adhesion (ISO 4624), cross-cut (ISO 2409) and film thickness (ISO 2808 / ISO 19840).
• Reporting: Test report requirements include photographic documentation, measured dry film thickness, zinc layer thickness (for galvanized substrates), thermal‑sprayed coating thickness, and detailed test conditions.

Applications and Users

ISO 12944-6:2018 is practical for:

• Asset owners, engineers and designers selecting paint systems for bridges, offshore structures, industrial plants and infrastructure.
• Coating manufacturers and suppliers validating product performance in laboratory conditions.
• Contractors and specifiers preparing tender specifications and performance requirements.
• Inspection and testing laboratories conducting standardized assessments and preparing compliant test reports. The standard helps compare systems under controlled conditions, supporting informed decisions on protective paint system selection and specification.

Related Standards

Relevant ISO documents referenced in ISO 12944-6:2018:

• ISO 12944 series (general, classification of environments)
• ISO 9227 (salt spray)
• ISO 6270‑1 (condensation humidity)
• ISO 1461 (hot dip galvanizing)
• ISO 2063‑1 / ‑2 (thermal spraying)
• ISO 4628 series, ISO 4624, ISO 2409, ISO 2808, ISO 19840

Use ISO 12944-6:2018 when you need standardized laboratory test methods to evaluate and compare corrosion protection performance of paint systems for steel structures.