Is your t-shirt really madeof 100 percent U.S. cotton? The Department of Energy is working on a way for U.S. Customs to be sure that it is. Counterfeiters and trade law violators cost the U.S. millions every year by faking country-of-origin certification in order to avoid U.S. import tariffs. Oak Ridge National Laboratory, in Tennessee, has developed an invisible tagging system that will allow manufacturers of raw textiles to embed date and place of manufacture information in the fabrics themselves. Invisible 2-D bar codes, or geometric figures, are transferred onto the raw textiles with a near-infrared dye. Customs need only scan a garment with an infrared reader to get encoded information on its historyfrom raw materials to factory to U.S. port of entry. According to ORNL, this new technology is nearly impossible for a counterfeiter to fakethe bar codes alone can contain millions of letter and number combinationsand the dye can survive all stages of garment manufacturing, including bleaching and mercerizing.