black artefacts


I modelised a 3D logo but when rendering it it gives me some black artefacts mainly visible on the “G” letter (see attached picture)
I already recalculated normals and removed doubles, but it doesn’t solve the issue.
Do you have any idea how I can solve that issue?

I used Minnaert and WardIso.
I would like to give my logo a metallic look.




go into editmode, Press W and “remove doubles” then select all and press Cntrl-N to recalc normals outside.

You can add an edge-split modifier and auto-smooth to get rid of it too.

Might want to post this in the Modeling support forum next time though.