Lifting this stamp (removing it and then putting it back in place with a stamp hinge) can be a legitimate option for two reasons. First, to ID the stamp. Second and perhaps more importantly, it will reduce the acidification risk that may be going on with the cover. Many covers were manufactured with less expensive low quality paper which contain large amounts of acid forming Lignin; these covers become toned (yellowed, brown, and brittle) and typically they will also tone the stamps on them.
There are some covers in which lifting the stamp is not a good idea. In these cases taking steps to neutralizing the entire cover is a better solution.
Learn more at
https://www.loc.gov/preservation/ca...rochure.htmlHere is what happens to paper after years of acidification
Don
Posted 09/22/2017 12:03 am
