I've no idea. But I was thinking this could be a way to destroy a hard drive without having to erase and rewrite over it multiple times. Many people have responded to say that it won't erase the hard drive; I appreciate everyone who answered my question!
The best way to destroy the data on platter drive storage is to hit them with a heavy duty oscillating magnetic field which rapidly changes poles, then open the case, bend the platters completely out of true flatness, scratch the surfaces as much as possible (both sides). then dump the whole set of platters in fuel oil. . . that dissolves the magnetic substrate which holds the data and strips it from the aluminum platters. . . if you really want to be certain. Burn the fuel oil with the hard drives still in it. I guarantee even the CIA will not be able to retrieve anything from the remnants of the mess that is usable. Of course, they won't need to. They'll probably already have a copy of everything on your drives. . . with back ups at the NSA.