Percival P. Cassidy wrote:
What's the best paint stripper for a few decades' worth of paint on a
steel door?

The top layer or two peel off the underlying layer in sheets once I get
a finger nail under them, but Bix Original Stripper doesn't seem to be
doing a lot (and it seems to me that it smells different from the
identically labeled stuff I've used before). I also tried some
orange-colored citrus-based stuff that was on clearance, but it doesn't
do a whole lot of good either.

methylene chloride is the old fashioned tried and true paint stripper.
I have used it many times and it will remove the toughtest paint. It
is wicked dangerous stuff, though and has to be treated with the
greatest respect. Ventilation, long sleeves, rubber gloves, safety
googgles are all musts. but if you want to get the job done this
stuff will do it and it is cheaper than the newer stuff. check this
link for more info:

http://www.cpsc.gov/cpscpub/pubs/423.html