Creating Man-made Materials in Cycles - Blender 2.6 Cycles: Materials and Textures - page 130

Now we must expose all the values necessary to tweak the node group
for different types of metals.
8. Click and drag the IOR input socket of the Fresnel node to the extreme
left border of the group envelope.
9. Do the same with the Color1 input socket of the Add node, renaming
the newly appeared slot, Color ; also drag the Color2 socket of the Add
node to the same Color interface socket.
10. Drag the Roughness input socket of the Glossy shader to the same in-
terface socket, then do the same with the Roughness socket of the An-
isotropic shader.
11. Click and drag the Fac socket of the first Mix Shader node to the envel-
ope border, rename it Aniso_Amount .
12. Click and drag the Anisotropy socket of the Anisotropic shader.
13. Repeat the same for the Rotation input socket.
14. Now click and drag the Height socket of the Bump node, renaming it
Bump .
15. Do the same for the Strength socket, renaming it Bump_Strength .
16. Lastly, click and drag the Tangent input socket of the Anisotropic
shader.
How it works...
The effect of this node group is mainly based on the IOR value, which is usually quite
different for the different metals.