 The glue, according to paper scholar Hans Lenz, was made from the roots of Orchidaceae plants and guanacaste sap.Next, the "tlacuilo" applied a gesso to fill the paper's pores and make the surface more even, but only on the obverse side.The "tlacuilo" then drafted the entirety of the codex in pale black ink, then tied the glyphs and date blocks together with a draft line of red ink.