ISO 15711:2003

Overview

ISO 15711:2003 - Paints and varnishes: Determination of resistance to cathodic disbonding of coatings exposed to sea water - specifies two laboratory test methods to assess how organic coatings on metallic substrates resist cathodic disbonding under sea‑water exposure. The standard targets coatings used on ships and marine structures and is explicit that the methods are not suitable for land‑based structures. Tests are intended for comparative evaluation rather than routine quality control (long‑term exposure is recommended).

Key topics and technical requirements

• Two test methods
  • Method A (Impressed current / potentiostatic): Uses a cathodic protection circuit with a potentiostat (or galvanostat) to control the test substrate potential (specified target ~ −1 050 mV vs saturated calomel electrode). Requires an inert tank, reference electrode, graphite/platinum anode and voltage monitoring.
  • Method B (Sacrificial anode): Uses zinc sacrificial anodes attached to panels to emulate shipboard cathodic protection (target potential ~ −1 040 ± 10 mV vs saturated calomel). Reflects practical protection used on vessels.
• Test specimens and defects
  • Panels are prepared to representative substrate conditions; Method B uses four panels per coating (two protected, two controls) with defined artificial defects.
• Exposure media
  • Artificial sea water formulation is specified (e.g., NaCl 23.0 g/L, MgCl2·6H2O 9.8 g/L, Na2SO4·10H2O 8.9 g/L, CaCl2 1.2 g/L) unless natural sea water is agreed.
• Duration and evaluation
  • Tests are long‑term (recommendation: at least 26 weeks; Method B describes six months immersion). Assessment uses blistering, creep from defect and adhesion criteria referenced to ISO 12944-6, ISO 4628-2 and ISO 4624.
• Annexes
  • Annex A lists required supplementary information; Annex B provides zinc anode composition guidance.

Practical applications and users

ISO 15711:2003 is used by:

• Marine coating manufacturers and R&D teams assessing resistance to cathodic disbonding.
• Shipyards, marine engineers and specifiers evaluating coating systems for hulls, offshore platforms and other structures exposed to sea water.
• Test laboratories performing standardized comparative testing for product development, qualification and procurement specifications.

Benefits:

• Simulates real cathodic protection scenarios (impressed current and sacrificial anode).
• Provides repeatable, internationally recognized methods for comparing coating performance in marine environments.

Related standards

• ISO 12944-6 (laboratory performance test methods for protective paint systems)
• ISO 4628-2, ISO 4624 (evaluation of degradation and adhesion)
• ISO 1513, ISO 1514, ISO 3696 (sample/panel preparation and water quality)

Keywords: ISO 15711:2003, cathodic disbonding, marine coatings, sea water, cathodic protection, sacrificial anode, impressed current, paint testing.