Flipping Normals issue under Multires

I understand that this operation is likely not supported, as editing the mesh while sculpting can cause all sorts of problems, but anyway–

I have a character mesh that I’m currently sculpting. I started sculpting with only Multires modifier on (I mirror the mesh manually by duplicating so the tris are the same on both sides). I tend to make changes to the shape of the character on the fly, so I like going into Edit mode and moving verts with Proportional on. I’m usually aware that I need to move the same verts on both sides, but I forgot to move one arm before I started sculpting on the hands.

I’ve deleted the erroneous arm and mirrored over the good one. The mesh mirrors over fine, but the normals are flipped. I flip the normals, but the normals still remain flipped on the Z. Is there any way to flip normals on just the Z? I know the arm looks rather funky, but I can see the data is still perfectly intact, just flipped upside down.


I had to do this once before (in 2.61). I dont know if it will work in 2.65 or not.

1st thing: Ctrl-A (Apply Scale/Rotation)

Then: Flip normals inward BEFORE you mirror (you may need to separate the mesh into 2 objects, I cant remember). After you flip the mesh, normals should appear correctly oriented. It took me 3-4 tries to get it right, even though it seems straight forward. I don’t remember what was causing the problem but I do remember it being very tricky for some reason (maybe a seam where the new pieces meet?). I recommend saving the file before trying this. Good luck!