The first polyester fibers were produced by reacting ethylene glycol and either terephthalic acid or one of its esters to give poly(ethylene terephthalate). This polymer is still used to make thin films (Mylar) and textile fibers (Dacron and Fortrel).
This stamp also may be used for mailing items weighing up to 2-ounces. These Forever stamps will always be equal in value to the applicable price for the price category printed on them, at the time of use. The initial price and value for this stamp is 71 cents, effective May 31.
A: Customers can use Forever stamps for international mail, but since all international prices are higher than domestic prices, customers will need to attach additional postage. The value of the Forever stamp is the domestic First-Class Mail 1-ounce letter price in effect on the day of use. I have mailed internationally and to Canada with Forever stamps. The woman at the window could tell me the actual value of the Forever stamp when I bought it.