Just for the PC record, I’ve been casting an MP mold lately and compared Harbor Freight white (which has a bad reputation, but I’ve used and it does work), with Sherwin Williams Powdura powder coat - which I picked up cheap on EBay recently (for $13 shipped per lb).
Both are shake and bake, both are completely coated, but the Powdura got much better coverage with much less shaking.
You can tell which is which! Just thought folks might be interested.
Pete