How can the demarcation between two materials be smoothed? After assigning two different materials to a subdivded mesh, I would like to smooth the demarcation between them from:

To something like:



I tried to isolate one material and selected the outline using Select / Non Manifold
and hoped that I could rotate the edges around z-axis with individual origins but this didn't work as expected.



How can the edges be smoothed as in the 2nd image (preferably without separating the mesh before) ?
You can try the Relax operator of Loop Tools (a bundled addon):

To use:

Enable the addon in CtrlAltU&gt; User Preferences &gt; Addons:


Then run it by pressing W&gt; LoopTools &gt; Relax.