You can use any electric coffee or spice grinder to get an arbitrarily fine salt grind. The longer you grind it the finer it will get, and since salt is not very tough to grind it doesn't take long at all.

I use a cheap spice grinder to turn salt into a fine powder for using on popcorn.

You can use any electric coffee or spice grinder to get an arbitrarily fine salt grind. The longer you grind it the finer it will get, and since salt is not very tough to grind it doesn't take long at all especially if you start with standard table salt which is already pretty small in grain size.

I use a cheap spice grinder to turn salt into a fine powder for using on popcorn.