I just came across what to me at least is a set of tools from
Gesswein for dealing with porosity. They are called “Porosity
Removers.” What follows is from the Gesswein description of the
tools.
"Rotary Burnishers for platinum, gold and silver
The fastest and most effective tools for removing porosity and
scratches. Patented creations, these rotary burnishers are made of
highly polished tungsten carbide and mounted on 3/32 shanks. Each
burnisher has a 12-, 18-, or 36-flute sidewall that produces its own
unique effect on metals. The 12- flute burnisher leaves a coarse
finish and covers large pinholes on gold and silver; the 18-flute
burnisher leaves a medium finish and covers moderate pinholes on all
metals; and the 36-flute burnishers leave a fine finish and covers
small pinholes on all metals."
There are 12, 18, & 36 flute burnshers that measure 5x13 mm and an 18
and 36 flute burnisher that measures 10x7 mm. Prices range from $45
to $69.95 each (US $).
Rather pricey, but I thought I would mention it as there has been
some considerable discussion on tools and methods for dealing with
porosity.
B Goodman in Beautiful BC