slip Sleep Mask in Blue. The stars have aligned. Embark on a celestial slumber with this Zodiac-inspired silk sleep mask. The beauty secret of celebrity hairstylists, dermatologists and beauty experts. What could be better than sleeping on a slipsilk pillowcase? Wearing a luxurious slipsilk sleep mask at the same time (so your beauty sleep isn't interrupted).. Designed to help you get your uninterrupted beauty sleep. Made from 100% highest grade (6A) long fiber mulberry silk. Do not machine wash. Use a pH neutral liquid detergent and hand wash.. Measures approx 8.1 W x 3.3 H. Use up to 8 hours daily for maximum results.. SLIP-WU71. 810046984574. In 2003, slip Co-Founder and CEO Fiona Stewart was prescribed acne medication which resulted in extremely sensitive skin and thinning hair. Her dermatologist suggested sleeping on a silk pillowcase. Unable to find one, she sourced the best silk she could find and wrapped it around her pillow. The results were dramatic and immediate, she's never looked back. She had stumbled upon a long-forgotten beauty secret - and slip was born.