When applying corrosion protection outdoors, the surface must be checked for potential salt contamination before painting. This is because salt deposits can severely impair adhesion and therefore the quality of the coating.
According to ISO standards 8502-6 and 8502-9, the Bresle method is the industry standard for this kind of testing. The US Navy, the International Maritime Organization and other national standards also regulate the Bresle test.
The Bresle method is based on the fact that salt ions, in relation to their concentration, increase the electrical conductivity of water. This increase in conductivity is particularly noticeable with sodium chloride, the main salt in seawater, which makes it easy to measure.
For the measurement, a special patch is applied to the surface. The patch forms a kind of pocket that is then filled with water or another solvent using a syringe.
After a defined time period – during which any salts present on the surface dissolve – the liquid is drawn up again into the syringe and dripped into the salt tester. The instrument measures the conductivity and calculates from that the concentration of sodium chloride.
The salt concentration is dependent on the area covered by the patch and the amount of solvent used. Please ensure that the specified volume is drawn up correctly into the syringe and injected completely into the patch! So that the salts dissolve completely, the liquid should be drawn up 3-4 times and re-injected.