We do that in the museum with nitrogen.  This is a completely
nontoxic method.  The objects are placed in makeshift tents made
of plastic (oxygen proof) and the oxygen is processed out of
the tent and replaced with nitrogen.  See for an example
http://www.consolidas.de/en/technology 

Kind regards,
Gerhard Dangel - Augustinermuseum
Freiburg, Germany
http://www.freiburg.de/museen