For whitening white leathers, sometimes I find that the magic eraser works very well to remove the marks from the surfaces. When it ends up removing the colour though, this will work in a pinch. It does not appear to be completely waterproof, but it seems to stay in place during normal wear and tear. It does need a little bit of effort to blend it in, but it will make leathers look better than before. For more permanence, the scuff cover might be better.