Parchment, well vellum, is interesting. There's still a company or two producing it in the UK as all UK law is published on vellum, as it's been shown to last t

Parchment, well vellum, is interesting. There's still a company or two producing it in the UK as all UK law is published on vellum, as it's been shown to last thousands of years. When they've looked at switching to archival paper, it's not been much cheaper, and only that it should last. Parchment also has a fair amount of natural fire resistance.