Tumbling will not change the internal porosity of the material,
however it will close off surface pores somewhat. It will also
compact and burnish the surface making the silver appear shiny.
This is not to be confused with a “mirror finish”. Although the piece
will be shiny, tumbling will leave a faint “orange peel” texture if
you look closely. A smooth mirror finish is achieved through sanding
and polishing. (again, this does not impact the basic porosity of the
material, just it’s appearance.)