The brass etched boxed walkway material surrounding the bridge looks superb
......how are you going to treat this?.......
A chemical process...[blackening] can turn this to any shade of greenish/bronze/black and is only a surface change to a few micron in depth and a few micron as an oxidised surface finish
To the naked eye, you would never perceive any change in the mesh plate surface width, depth or thickness of the cross sections
On the real vessel, I suspect any rain or spray water would simply fall through the mesh, then through boxed in scupper plates and drains to the main deck level
Derek