Question

Why must we observe a freshly cut surface of a materials to see whether it is lustrous or not?

Answer 1

Answer:

If we find a surface that is not newly cut, we can get the wrong results. The surface is not a new cut, dust, rust and other materials may be deposited by layers. Reduce the softness of the surface. For example, iron shines very much on a new cut. But it is absorbed by a bright red-brown finish at the end of the end of the turkey, which does not shine. It gives the viewer the impression that iron is not exciting. Therefore, we have a new cut surface to see whether it is lustrous or not.