After some practice with procedural textures in cycles?I created the copper material, from startr to finish, applying the knowledge acquired thanks to Kent Trammell classes and Eduardo Maldonado blog. In this material, I have put a lot of controls to configure various values. This material can be used for new or old copper just changing some parameters in the material.
I am very happy with this shader because with small adjustments like color may be used for other metals, eg brass
BTW: I miss some kind of separator for inputs in groups to keep everything organized
Here you can download it if you like it ;)
(You can use it commercially in your models.You can not sell it as is, with minor modifications or included in repacks etc..)