This Glow in the dark polyester thread has been treated with a bright, glowing pigment which absorbs light and glows for several hours after being charged for approximately 15 minutes. It is a great way to add fun and personality to all kinds of your embroidery projects. Available in 12 colours. Tip: To get a good glow effect, use thread liberally. The more thread you put in an area, the more glow you will get.