Theres also a method of using a 20:1 water/molasses solution,though that can take a week or two of soaking.Apparently you buy bulk molasses from a feed store.Seen some pretty amazing rust clean ups with it.More molasses faster it works.

Some folks shy away from blasting r/t getting things imbedded into pan,or sending it out to be done and they use a contaminated medium on your pan.

Electrolysis has lots of fans out there who flat out love the results.

Gotta say Im a huge cast iron fan.