Corrosion study of industrial painting cycles for garden furniture

Different cycles of industrial painting of steel and galvanised steel for making garden furniture were studied in order to overcome problems in covering tips, edges, sharp corners, commonly found in practice. Painting cycles, including cataphoresis or a Brugal® treatment, were used. The following characterisation was carried out: (a) measurement of the film thickness of the coating; (b) evaluation of the defects in the organic coating; (c) corrosion resistance in a salt fog chamber according to ASTM standard B 117 and (d) electrochemical impedance measurements. In general terms, test have yielded good results in assessing the best performance with different industrial cycles of painting. Good performance of every cycle has been shown in geometrically simple samples (tubes externally coated), while the corrosion behaviour of geometrically complex shapes (stretched net, round-drilled and stamped sheets) strictly depends on the selected painting cycle. The experimental results showed the effectiveness of the cataphoretic primer in increasing metal substrate coverage, so increasing corrosion resistance. The same was not obtained by using a Brugal® pre-treatment. Galvanised steel performed better than not galvanised one in the salt fog chamber test, but this result was not confirmed by electrochemical impedance spectroscopy (EIS) data. This electrochemical technique confirmed to be really a useful tool to clarify the behaviour of protected samples under accelerated corrosion conditions. © 2002 Published by Elsevier Science B.V.