amatl (Mdz23r)

This square piece of paper differs from the rolls of white paper with ties that are more standard in the Codex Mendoza. Thus, its color and square shape are both worth noting. Today, one can purchase rectangles of amatl, and they come in multiple colors including a natural, undyed color, which can also be brown. But most early amatl was either naturally lighter in color or it was whitewashed. Here's a sample page from the sixteenth-century Codex Boturini, one that was not whitewashed.