http://www.czsewingthread.com/sewing-thread/bright-sewing-thread/ Brighter heat set sewing thread The bright heat set sewing thread is description of the sewing thread from raw material and final reprocessing. First aspect is from raw material, and the brighter word of brighter heat set sewing thread means the fibre is bright not semi-dull or dull. The second aspect is heat set , which means putting the yarn in a heat machine to steam them. And the final sewing thread can be used directly , no dying. The price is more expensive than it of the sewing thread without heat set . Bright Sewing Thread quotation website:http://www.czsewingthread.com/sewing-thread/bright-sewing-thread/