Preparation of porcelain surface for repair with JB Weld

[dough77494]

When using JB Kwik Weld to repair small holes in the outer tub of a Maytag LA506, what is the preferred way to prepare the porcelain surface e.g., sand the area to bare metal, rough up the surface with 220 sand paper, leaving as much porcelain as possible, or other?

The complete bottom inner surface of the outer tub will be coated with KBS Rust Seal as will the outer surface of the repaired area.