L.C. Silk Pure Silk Pillowcase Standard/queen (Ivory) 100% Pure Silk. Silk is by far the most comfortable natural material. Soft, smooth, and responsive, it is the ideal choice for bedding. Silk is a porous fiber which allows the material to breathe and evaporate moisture to provide a more restful sleep. Silk naturally adjusts to the temperature of your body to prevent over heating. Silk is well known for year-round comfort. Silk is a light fiber that provides warmth without bulk. Silk is inhospitable to dust mites. Silk is naturally hypoallergenic.