I've used Wei T'o (the spray version) on newspaper and old books.
I chose the spray version because I didn't have the nerve to
submerge old paper into a bath. I chose Wei T'o only after
talking to a number of people who had used it, including Bob
McWilliams at Light Impressions--who has used it in both museums
and on some old books that he personally owns. As to the long
term effects, who knows--I'm no scientist.
Regarding scrap books: We have old scrap books that have
clippings glued in--the glue eventually lets go. However,
clippings that we collect today are simply saved in acid free
envelopes.
John Handley
Museum of Ophthalmology