[HO455]

Basically once steel has left the mill it will start to rust unless coated with something. Once the rolls of sheet metal have been stamped and formed to shape the rusting begins on a microscopic level. So from that point on coatings are used to seal the metal from being exposed to moisture and oxygen and slow the rusting. OE make choices to meet cost and reputation requirements.

Once the factory coatings fail this is where folks opinions and experiences differ as to what to do for good results.

Your decision is how much metal do I want to remove in order to have the least amount of rust remaining. Sandblasting and grinding make your panels thinner.

Then what product/process will seal the metal from moisture and oxygen. Then what top coat will work with your sealing product?

Every step requires various amounts of preparation work sometimes before application or after application of a product or both.

Good luck and keep us in the loop.