I posted this link on another stamp board and thought it would be useful here. https://stamps.org/preservation-and-care Vince
FYI, just highlight the link and click on the "link" button below to make it a hyperlink. https://www.postalmuseum.org/discover/collections/philatelic-collection/caring-stamps-postal-history/
A few more... http://www.loc.gov/preservation/care/paper.html http://www.niso.org/publications/tr/tr01.pdf Don