grainy Texture after a while


after working for a while with blender 2.65a some textures get grainy when rendering it.
I´ve no Idea what it could be and hope somebody here can help me.

Thanks for your answers

This is a rendered picture after recognizing this grainyy textures.

You may have overlapping faces.

  • Remove any duplicated objects.
  • Select all vertices and remove doubles (W / remove doubles) then recalculate normals (select all faces and Ctrl+N)

Thank you for your quick reply,
but I can´t remove all the doubles because I created every single cube as a new object. Could it be that?
If I follow your advice with the ‘‘grainy’’ cube it changes nothing.

did you do as advised?

I cannot remove the doubles of all cubes because every cube is a single object and i can just edit once a time.
But even if i could remove all the doubles, i couldn’t move a single cube anymore, because after removing the doubles they stick together.
But why does this problem come up? How can I prevent it from coming up?

PS: How i said i created every cube as a single object in object mode or duplicated it from another cube, could this cause that problem?

Upload your blend file to
Ensure you have packed all your textures in your blend file first using the File / External Data menu

I hope I ensured all files in my .blend file.
Here is the link to it:

Richard Marklew already told that - remove any duplicated objects.
You have 3 cubes taking in one spot where it renders with blackness around. That is against computer logics - it can’t decide which cube to render and you have what you have here. Just move faulty rendered cube - you’ll see another in there; move that and another one appears.
Remove duplicated objects - taking one 3d space part.

Thank you very much,

I didn´t recognized this duplication, so it was my fault. :slight_smile: