All of the versions are on machine-produced rag paper, made from a combination of linen and cotton fibers. They're all written in iron gall ink, one of the most ubiquitous inks of the time, except for the first version, which is in both iron gall ink and pencil. To keep the ink from absorbing into the paper and thus bleeding, most of documents are coated in a thin layer of gelatin. The first known document was written prior to the address, while the second was written either shortly before or (more likely) shortly after the address, Michelle Krowl, Civil War and Reconstruction specialist at the Library of Congress' Manuscript Division, tells Popular Science. The last three versions were written by Lincoln in 1864 as charitable donations.