Clear rust on dark paint.

In my Tsushima diorama, i had to apply the rust on a white paint -this went quite smoothly, but if I had to apply the rust on a black or dark coloured ship the things would have been different. I have been observing the fences near my home and it seems that before attacking the metal, the rsut, first discolour the paint near the rust's borders. So here's my discoloured green mix; I added some yellow for the discoloured areas that will be situated in full sunlight.