Carolyn --
   Check in an inconspicuous place first, but acetone squeezed out on a
quickly twirled Q-tip ought to get off the white-out before liquifying
it enough to merely drive it into the grain/pores of the substrate ;).
Good luck! You might try a scrape-off with an x-acto blade, to see if it
might just pop off, though unlikely from my experience.
   We use a water soluble varnish I got in the crafts area of Jo-Ann's
Fabrics, intended for decoupage. I can't guarantee it's completely P.C.,
but IMHO it is reversible should the need arise. I use Pigma marker over
it after 1/2 hr drying time. Gaylord library supply catalogue carries white
permanent markers to go over dark surfaces - again suitable prepared with a
water-soluble varnish.
   Good luck dealing with the 'good' intentions of previous conservators/
registrars!
   Chris Bobbitt
   Curator of Collections
   Monros Co. Historical Museum
   Bloomington, IN 47408     [log in to unmask]