This is from a serious stamp-collector friend who has 40 years of
collection experience:

I would advise using Showgard or Scott stamp mounts, which come in many
different sizes for use with anything from a tiny stamp to a big sheet of
stamps.  They are available from most stamp dealers, or can be ordered from
specialized dealers in stamp collecting accessories who advertise in Linns
Stamp News.  (Measurements will be given in millimeters.)  They are
composed of an unbroken front sheet of transparent mylar (usually
non-reflective), backed by a piece of mylar the same size that has been cut
down the middle.  The backing is either transparent or black (black
normally looks better).  One places the stamp, sheet or cover in the mount
by separating the two pieces of backing a little, and then fastens the
mount in place by moistening the top piece of backing and placing it just
where it goes.  Both the top and bottom piece of backing are coated on the
back with an adhesive similar to the traditional adhesive on postage
stamps, but easier to remove when that is needed.

   If the material has any value,  avoid stamp hinges.  I use stamp hinges
myself on cheap cancelled stamps in an album, but for mint stamps, sheets,
etc., I use the mounts because they do not cause any damage.  Also, stamp
hinges will not take any weight, and anything fastened on with a stamp
hinge will curl unless it is kept between the pages of an album or other book.

There are some other transparent stamp mounts on the market that are
composed of the wrong materials, and will damage stamps if they are in them
long enough.  Showgard and Scott are both entirely safe, good for
centuries.

=========================================================
Important Subscriber Information:

The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ museum-l.html. You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] The body of the message should read "help" (without the quotes).

If you decide to leave Museum-L, please send a one line e-mail message to
[log in to unmask] The body of the message should read "Signoff
Museum-L" (without the quotes).