In accelerated aging studies, exposure to UV rays have been shown to cause fusibles to tan (darken). Especially on light colors, sheers or other light weight fabrics, and surface use, tanning may read as a color shift or dark spots. But now there???s Mistyfuse Ultraviolet! Mistyfuse Ultraviolet is specially formulated with an effective retardant to protect against the tanning effect of UV rays - without sacrificing any of the inherent Mistyfuse qualities you expect and trust. Mistyfuse Ultraviolet™ is white and fuses clear. Size: 20" x 90"