Avery Glue Stic for Envelopes, Disappearing Purple Color, 0.26 oz., Nontoxic, Permanent Adhesive, 3 Glue Sticks (00134) Envelope glue seals envelopes with a strong, permanent adhesive Goes on purple, dries clear; apply the right amount of adhesive with an easy-to-see purple glue that disappears once dry Doesn't bleed through delicate paper; a superior choice to liquid glue Glue adheres smoothly, minimizing any clumping or wrinkling Nontoxic acid-free glue is safe to use and easily washes off hands and clothing