I just received my first PCB back from the manufacturer. After soldering on the SMT components I found that the board works absolutely fine. The only thing I'm puzzled about is that both the ground pour and the traces are a brown color and not the green I would expect it to be since I specified a green solder mask. This is what it looks like:
I've tested the resistance of the ground pour between two points and it is not conductive, so this does not appear to be pure copper. However, since this is my first PCB I am really puzzled about the brown color. Does anyone have an explanation?