Hi I use a product put out by Griffith called "Silver-Black".
I've had this bottle for years & it has not lost it's strenght.
It seems to work best if you put a brushed finish on your piece.
I have a 3M flap wheel I use, works great, also very good at
taking off fire scale. I've found that if your piece is highly
polished the finish has motley affect. After I finish my piece I
apply 3 coats of Renaisance wax. :-)Win