Oh no man. Cast iron geekery is full of weird theories about why the old stuff is so smooth. The most popular one is that old pans were “machined” to get a smooth surface. No detail as to what sort of machining. So smart guys said “hey, I can machine it with sand paper”.
Though the more recent thing seems to be claiming that the old foundries used hard molds instead of sand.
Actual word from the Cast Iron industry and history would seem to be that until 50 years ago most of these companies were based on specific beaches of the Great Lakes where the sand was finer. Leading to tighter molds and smoother surfaces. Plus a half century of abrasive use you get crazy smooth pan. But whatever the hell the history is, sanding that shit out turns out to be an awesome way to a slick pan.
These things are nearly indestructible. Its a lump of iron, and there’s almost no way you could sand away enough metal to risk the pan, so why not?
