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.
Value of a Forever Stamp. The value of a Forever stamp is always set as the first-class mail rate. When Forever stamps were introduced in 2007, their value was 41 cents. On May 12, 2008, the cost of a first-class stamp increased to 42 cents, and on May 11, 2009, the cost of a first-class stamp increased to 44 cents. The value of a Forever stamp increased accordingly.