How can I tell if it has been over-sanded?

You can recognise over-sanding when the surface starts to behave unevenly: the pattern changes, lighter or darker patches appear, or you may sand through to the underlying layer. Checking the surface with your hand is often more reliable than a distant look – the surface should be smooth, without any protrusions, but not sanded through. You can detect over-sanding by running your hand over the surface. The surface should be free of all protrusions and be smooth.