Here's the info from the Glowy page on our website:Make any Halloween costume or other sewn item stand out in the crowd using this fun, special effect thread! Its lasting luminosity is ideal for creating that super spooky effect at night. Glowy™ threads can also create a fascinating look on sportswear or promotional items - for striking logos that are hard to ignore. Light, whether sunlight or artificial light, is stored in the yarn and emitted in the dark. All colors glow a greenish hue. For best results use Sulky 60 Wt. Bobbin Thread.
Important: Thread's intensity of fluorescence depends on the length of time it's been exposed to light. Glow lasts approximately 15-20 minutes depending on the length of exposure. Tests have shown NO loss of luminosity after 50 washings.
There is also a six-pack of colors available. They all glow the same greenish hue, but it's nice to have different colors for daylight in a design. AND... they are all on sale today 10/6/2021.
You do need a 90/14 topstitch needle for this thread. An 80/12 topstitch needle may work, too. (Topstitch needles have a longer eye.)