What Wheel do i place on my 6" Bench Grinder to Polish Sterling SIlver Felt or Cotton??

Actually, you need a high grade cotton if it's a fine finish you want. However, there is another way that often works well and doesn't remove the silver. place a piece of aluminum foil in the bottom of a pan large enough to dunk the item you want cleaned. Add water, and a table spoon of baking soda per liter of water. Heat the mixture to just about boiling, dip the piece in the water, making sure it makes contact with the aluminum foil. Generally, the piece will be cleaned within ten seconds. Severe cases take a little longer, and you might need to add more baking soda and change out the foil. This gets most of the oxidation off. A quick polish by hand after that, and it's good to go.

I don't think it is the material of the wheel that determines the result but the polishing compound you put on the wheel.

Look up Woodstock buffing compounds online. As I remember the rouge is the best for a mirror finish.

I have found that using felt will cause wear spots on whatever I polish. I use the cotton rag wheel.