Black and Skin?

Ok heres my question.

I toke the tutorial on facemaking, so i decided to try it out in the game engine.I Vertic painted the whole thing skin colour, and twosided faces
but when i press alt z some of the faces are black and some are skin colour.

I figured out that if I select a black face and flip normals it turns skin colour,but i got 1000 faces and i dont want to do each face one by one.
Plus if i select all the faces and click flip normals the ones that are black turn skin and the ones that are skin turn black.

So how do you have all faces that one colour?

In editmode try mesh->normals->recalculate outside. I’m sure that’s what it’s designed for. There are a few times that hasn’t worked for me though.

If it doesn’t work, flip all the faces until there is a minimum amount the wrong way round. Now go into UVfaceselect mode and select the faces you want to flip. Then go to editmode and flip 'em. This is the long way but the face select makes it easier - Blender 2.35’s new select tools will help when it arrives.