Weathering phenomena represent a topic of growing interest in computer graphics, and corrosion reactions are of great importance since they affect a large number of different fields. Previous investigations have essentially dealt with the modeling and rendering of metallic patinas. We propose an approach based on simple physical characteristics to simulate and render new forms of corrosion. We take into account "real world" time and different atmospheric condition categories with experimental data. This allows us to predict the evolution of corrosion over time. The reaction is simulated using a random walk technique adapted to our generic model. For realistic rendering, we propose a BRDF and (color- and bump-) texture models, thus affecting color, reflectance and geometry. We additionally propose a set of rules to automatically predict the preferential starting locations of corrosion. Key words: Rendering, corrosion, natural phenomena, texturing, BRDF.