I have found that the corn cob works really well on the parts I have just nickel plated. I have added some brasso to the media and it works well but i would lile to try flitz.
I think corncob is what you should be using post nickel plating. Flitz is the only product I use in my tumbler. I've used Brasso and Novus 3, which work well but take twice as long to polish to the level Flitz does in half the time.
Where did you find the corn cob media ?
I bought it from the local gun smith.
Its a box of Lyman corn cob media, 2 pounds cost me $22
