Oil-based coatings can be used to enhance the corrosion resistance of metals and therefore increase their lifetime. Such oils can be applied either by spraying or by using a brush on metal substrates in their real application environments. Recently we performed an accelerated corrosion test on different oil-based coating products for our client Sia Auto Truck Studio, who were particularly interested in the performance of a spray-type oil based coating – an NHOU Rust Prevention Spray. As the name suggests, the coating can be sprayed on the substrate directly from the bottle, which creates an uniform coating. This is achieved by using a proper combination of oil viscosity and spray bottle design, which creates an expanding cone of expelled oil particles, that create a defect free coating on the metal substrate. The corrosion test was performed on 90×90 mm low carbon steel plates, that are extremely vulnerable to corrosion. For testing, the Machu test was used, which is essentially an accelerated corrosion test in an acidified salt solution with hydrogen peroxide. This test allows to obtain results already within 48 hours, which is useful for quickly gaining feedback on the performance of materials and coatings before carrying out long-term immersion or salt spray tests. As can be seen from the photo in Figure 1, the coated sample remained relatively unharmed after the test, exhibiting only a few individual sites of corrosion in the central area. Only the edge of the sample suffered damage from corrosion as it was problematic to coat for this particular test. Overall, the coating exhibited good performance and should therefore be tested further with long-term immersion and salt spray tests, electrochemical techniques and finally in real application environment.
