Scrape off loose rust with a metal spatula or scraper
Scrub the rusted area with a grill stone, pumice stone, or fine steel wool
Apply a thin layer of cooking oil to the surface
Heat the Blackstone until warm
Use a mixture of white vinegar and water on stubborn rust spots
Scrub again with a non-abrasive pad
Wipe the surface clean with paper towels or a cloth
Dry the griddle completely
Re-season the surface with a thin coat of oil
Heat the griddle until the oil bonds to the surface
Repeat seasoning layers if needed