Certainly, it was an old paper of some sort. And old blank paper isn’t all that common. Were I the forger, I’d start with an existing old map.
Not really. Manuscripts often have blank pages. As it happens, a case in point would be the Beinecke Hystoria Tartarorum, the volume into which the Map was bound when it first came to light. It has five blank folios at the end.
This is a pretty common forgery technique. Razor out a blank page from an authentic folio of the right age, and you’ve got a blank piece of paper of the right material and age.
Books were made out of large sheets of paper, folded once (folio) to make four pages, twice (quarto) to make eight pages, or thrice (octavo) to make 16 pages, which were then bound together. The amount of pages of actual material rarely matched up exactly with an even multiple of 4, 8, or 16, so books usually had extra blank pages. It was also not uncommon for a printer to deliberately include extra blank pages, for the purchaser to paste in their own illustrations, or take notes, or what have you. Blank sheets of 15th century paper/parchment/vellum aren’t all that hard to come by for a professional forger.
Another technique is to take a sheet that does have writing or printing on it, and scrape and clean the sheet to remove the ink, and then re-use it - a palimpsest. Given the scrutiny the Vinland Map has received, though, I don’t think this technique was used in this case. Evidence of previous ink and the process used to create the palimpsest would almost certainly have been found.
It seems quite unlikely to me that the Vinland Map is an edited version of an authentic 15th century mappa mundi. If Vinland isn’t there, there’s an awful lot of empty space on the left side of the map. The centering and spacing of the map only make sense if there’s supposed to be something to the west of Greenland, on the left margin of the map.
To be fair they don’t necessarily say 20th century A.D ink…
