Pasting Vertex Paint

I see that there is a Copy Vertex colours in the options of the vertex painting, (doing some here this morning). Now how do I paste them to the other side of my mesh? Can this be done? If not, then what is it there for?

BgDM

this is used in Face Select mode, not vertex painting mode. It copies the vertex color of the active face to the rest of the selected face.

Martin