This International Standard describes two methods for determining the ability of paint, or other organic coatings, applied to metallic substrates to withstand cathodic disbonding when the surface coating may contain or develop discontinuities. The methods are applicable to coatings that are exposed to sea water, such as those applied to ships or marine structures. They are not suitable for the assessment of the ability of coatings to withstand cathodic disbonding on land-based structures. Method A involves the use of a cathodic protection circuit, whereby the electrode potential of the test substrates is controlled potentiostatically. Method B involves the use of sacrificial anodes attached to the test substrates. This reflects the practical method of cathodic protection commonly used on ships.