Flash rust on sanded cast iron.
For those who have sanded cast iron skillets or Dutch ovens smooth, how do you handle the flash rust when you clean the sanded dust and particles from the finished surface? I washed my first one in cold water and soap before oiling and seasoning. When water touched the bare clean cast iron, rust flashed across it within a fraction of a second. With warm water it is even quicker. I rubbed off the rust as quickly as possible with an oily rag but didn't like having it rust at all.
I now sand with a minimal coat of grape oil and wipe/flush the finished surface with several washes of clean oil. That way the clean bare cast iron surface never is exposed to air or water and so does not flash rust. I’m not convinced that an oil wash gets all of the grit particles out of the cast iron pores, but I haven't noticed any.
Anyone got a better method of sanding smooth and cleaning while avoiding nearly instant rust when the bare metal loses its seasoning coat and is exposed to oxygen?
Just to be clear, sanding cast iron smooth is a one time process for each utensil, not some repeated cleaning event.