I’m modeling a chair right now. But when i’m merging the two axes of the chair these artifacts apear. I dont’t know why.
Delete any faces that are inside your mesh
Select all vertices and remove doubles, W / remove doubles
Select all vertices and recalculate normals, Ctrl+N
CTRL+N doesnt always work, sometimes screws stuff up even more!
show the display panel (N KEY). Under ‘DISPLAY’ field will be a section to show NORMALS. Click the ‘FACE’ Icon. . . blue lines show up all over your mesh. The ones that arent pointing with the rest of the mesh, select those faces, Wkey + FLIP NORMALS.
That will fix your problems!
It worked when i selected all vertecies and pressed CTRL+N. But the tip to show the normals was also helpful! Thanks great help here! 