wrote:

A rare book seller told me that a 400-year old book (that I
just found) was washed and rebound in the XIX century, to fit
the style of the library of the new owner. He said this was
a common practice back then.

Is this true ? How does that affect the book condition and
book value ?

I can't vouch for the commonness of the practice in the 19th century,
but I can confirm that many books up until about the end of the 17th
century (and perhaps later) were printed on a tough, ribbed kind of
paper that will indeed withstand washing. The main reason for doing it -
in my case, at least - is when books have become really gunky, perhaps
because they were left in dank cellars for many years, or something like
that.

Here is an account of my first adventure washing a 16th century book:

http://groups.google.com/group/rec.c... c0ad2d79bb1e
(http://tinyurl.com/2snpv5)

The book in question (along with a companion volume of the Aeneid) is
still on my shelves five years later. Compared with the smelly volumes
they once were, covered with unsightly brownish-yellow stains, the pages
are bright and fresh and well worth what I paid for them, whereas when I
first got them I reckon I'd got a pretty poor deal.

As for the rebinding, as long as it is in keeping with the book it won't
affect its value all that much; it's always a plus if a book from that
period is in its original binding, but it doesn't make that big a
difference to the value. Books of that period were generally bought
unbound and taken to the bindery by the　purchaser, so the book and its
binding don't belong together in quite the same way as they do with
later books.

By the way, what book is it?

John
http://rarebooksinjapan.org