Destroying a hard drive

[Jim Kuzdrall]

    What is the most efficient way to destroy the data on a hard drive 
before junking it?  Normal file erasure leaves the data intact.  Secure 
erasure or reformatting takes too much time, and the drive may not be 
working well enough to complete the operation.

   Another quick method suggested is a sledge hammer, but that seems 
"hit-or-miss" (sorry).  Without opening the case one cannot confirm 
whether all of the platters have been sufficiently damaged.

   Opening the drive and sanding, scratching, or bending the platters 
seems tedious.  Automated assembly uses non-reversible techniques such 
as press-fits, epoxy, rivets, etc. which may make it difficult to get 
at the surfaces.

    Has anybody suggested a chemical solvent wash?  (Wash fluid disposal 
might possibly be a problem.)

    Do the rather exotic magnetic coatings have a low enough Curie 
temperature to destroy the magnetization in an oven?  Our kitchen oven 
goes to 270C (520F) or so, but magnetite requires 560C.  Cobalt 
compounds are higher.  Using a Bernz-O-Matic torch would simplify 
disassembly - just remove the cover.

    Not that I have anything to hide, you understand.  Just curious.

Jim Kuzdrall