How to preserve pewter buttons/relics?

[Fossils]

Howdy folks. I recently found a few 18th century or so pewter flat buttons. Nothing military related or rare but something I'd still like to preserve. I noticed once of them has some slight crumbling at the edges. Is there a treatment yall would recommend to protect pewter relics? Thanks!

 

[Vermont treasure hunter]

50/50 solution of Elmers Glue and water. Let the items soak in it. Will help stop the crumbling.