Methods and systems that provide privacy of signatures on envelopes containing ballots are provided. The envelope for returning ballots includes a removable signature stub positioned on top of a signature area. The voter signs the back of the envelope on the signature stub, thereby imprinting a signature on the signature area by transferring a material from the signature stub to the signature area, and removes the signature stub. The signature is then covered by a label that conceals the signature under normal lighting conditions. To read the signature, light having a predetermined wavelength is directed onto the label, thereby rendering the label transparent and the signature visible.