Combining matte and glossy finishes

First of all, thanks to everyone who ever asked or answered a question here. I’m new to Blender and was able to get pretty far with my model just by reading previous posts. But now I’m stuck.

I’ve finished my model, converted to a mesh and UV unwrapped. The finish I want is about 95% flat copper patina, with 5% of shiny copper exposed where the patina has chipped off. My method so far has been to apply the patina over a flat gray material, then go in and change individual faces to the shiny copper material. This has resulted in a lot of subdivisions to get random, realistic looking chips with jagged edges. I was hoping there would be a way to make the whole model the shiny copper material, then cover with the patina and remove bits of that texture where I wanted. But covering the shiny copper with the patina resulted in a shiny patina. Is there a smarter way of doing this “chipped paint” effect combining flat and glossy finishes? Can a shiny copper be painted onto the flat patina texture image?

Again, thanks for everyone’s help.

I think specular maps is what your asking about…

You could try stencilling -

Or you could make the texture with Gimp or Photoshop.

Thanks for the quick responses. I’ve been looking into Nodes and looks like that might allow me to combine the glossy copper material with the flat patina material using the paintbrush. Unfortunately I’m having problems with the Node Editor window. No images will appear in the nodes, only gray checkerboards. And the lines connecting the nodes are invisible. Looks like I might need a new graphics card unless one of my settings is messed up. This happens even from the startup Cube screen.

UPDATE Nodes working now. Just needed an updated graphics card.