Whether for a superyacht or a shipyard crane: the durable coating of steel surfaces plays an important role in the maritime sector and other industries. The problem is that if the substrate is not properly prepared before coating, there is a risk of costly subsurface corrosion. Wrede Technologies (WRETEC) conducts laboratory analyses of coating defects and its reports provide a reliable basis for warranty claims.

Pavel Jeljakin, Project Manager and Material Scientist at Wrede Technologies GmbH, explains how defects can occur when steel substrates are coated: “It is crucial that steel surfaces are thoroughly cleaned before the primer is applied. If the substrate is not properly prepared, rust or other coating defects can occur.” As an example of this, the company recently had an order for a crane that exhibited extensive subsurface corrosion while still within the warranty period. In order to be able to assert any warranty claims against the manufacturer, the customer submitted material samples of the paint (paint chips) to WRETEC for laboratory testing. Jeljakin and his team used a 3D microscope to get to the root of the problem. To do so, they cast ten randomly selected paint chips in resin, polished them up and examined the cross-sectional area under a microscope. “When examining the coating cross-section, particles of metal were found under the primer layer in almost every sample. These may have been the cause of corrosion. In this case, the particles were an indicator of poor cleaning.” The findings from the analysis indicate that the steel component was not sufficiently cleaned after blasting and thus the 2.5 Sa level of surface preparation specified by the manufacturer, which describes the required cleanliness, was not met.