Pink By Design stamps are made in the U.S.A. from the highest quality photopolymer material. Our stamps are designed according to print industry standards to resist yellowing, to carry and transfer ink sharply, and should last a lifetime with proper care. They are also latex-free and contain no known ingredients that are harmful to you or the environment. The stamps will normally stay sticky and adhere to the blocks for years. If they do happen to lose their tack, simply clean them with clear stamp cleaner or you may wash them with soap and water. We love our stamps and believe that you will as well!