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: According to the U.S. Postal Service, the price of a first-class postage stamp in the United States is 49 cents as of June 2014. This rate applies to standard-sized mail weighing 1 ounce or less. Letters weighing more than 1 ounce cost an additional 21 cents to mail.