I can't speak to the archival qualities of foam peanuts, but I do know that
objects cushioned in them, especially wrapped as opposed to boxed items, can
and do migrate; I have seen them end up against each other or against the
side of the box.  I recommend boxing anything you will cushion with peanuts,
and packing the peanuts very tightly around the box.  Another technique is
to put a number of rigid spacers between the inner and outer boxes and fill
in the rest of the space with peanuts.
Anne Lane
Curatorial Assistant
Museum of York County
4621 Mt. Gallant Road
Rock Hill, SC  29732-9905
803-329-2121 ext 122  *  [log in to unmask]