Scrape off loose rust with a metal scraper or grill stone
Wash the surface with warm water and a small amount of dish soap
Scrub the rusted areas with a scouring pad or steel wool
Rinse and dry the Blackstone completely
Heat the griddle to remove any remaining moisture
Apply a thin layer of cooking oil
Wipe off excess oil with a clean paper towel
Heat the griddle until the oil bonds to the surface
Repeat oiling and heating to re-season the surface
Store the Blackstone in a dry place with a cover
Keep a light coat of oil on the surface after each use