Charge it with natural or artificial light for a few seconds and watch it glow for up to 6 hours, night after night. NiteLite ExtraGlow 40 wt. 100% polyester is dryer and iron safe (low/med. heat). Recommended for quilting and embroidery. Suggested needle: 90/14. NiteLite ExtraGlow Thread, 80 yards spool by Superior Threads.