Forgive me if I am suggesting something that you already know. After
piercing and filing with fine files the easiest way to polish the
inner faces of the piercing is by what is called stringing over
here in England. If this is something new to you I will explain.
I cut strips of thin leather approximately 10" x 1/8".
One end is secured in the bench vice and then the loose end is fed
through the piercing.
Using polishing compounds on the leather, the same as if you were on
the mop. Different leather strips for each compound.
Holding the loose end of the leather taught and running the piercing
up and down the leather polishes the inner surfaces fine. It take a
little time but work well.
In the past I have nailed a collection of strips to a piece of wood
to speed up the process, if switching from one compound to the
next. As you can see on my orchid gallery showcase I do a hell of a
lot of pierced work.
Regards James Miller