UV SunBlock for Fabrics The UV SunBlock protects fabrics, fibers and colored surfaces from the fading and damage caused by the Sun's rays. This unique formula absorbs the Sun's energy of UV radiation, and then releases it in a harmless form. Fabrics and other fibers keep their resiliency and colors remain vibrant. The UV SunBlock is safe to use on all types of materials including synthetics and will not change the texture of the fabric. UV Block works well with any mill treatment by adding an extra level of protection and is fast drying.