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.
â¢Stamps with any faults (creases, tears, thins, etc.) are worth far less than those in perfect condition. One thing that is common with most collectibles, especially stamps, is that condition is everything. The same stamp that normally sells for $100 may not even be worth $10 if there are creases, thins, tears, etc.