shutters were used during cold seasons. Fatimid Caliphate In the Fatimid Caliphate, a curtain known as a sitr ("veil") was used to conceal the caliph at the beginning of an audience session (majlis). A servant known as the ṣāḥib al-sitr (or muṭawallī al-sitr) would then pull it back to reveal the caliph seated on his throne. The sahib al-sitr was also combined with the duties of chamberlain, master of ceremonies, and bearer of the caliph's sword, and was often chosen from among mamluks from saqaliba backgrounds. Light control and insulation Curtains are manufactured from a variety of thick fabrics, each with a differing degree of light absorption and heat insulating qualities. For maximum temperature control, the curtain gap to the window should be small, with minimum convection drafts below or above the curtain. Various architectural structures around the curtain can minimize these air drafts, but usually they are just used for decoration and make rooms feel more cozy. A sheer or net curtain is one that is made from translucent fabric, such as a loosely woven polyester voile, silk or nylon made marquisette or ninon, and cotton lace, etc. Sheer curtains allow a majority of light to be transmitted through the fabric, with the fabric weave providing a basic level of UV protection while retaining maximum visibility outward through the curtain. Sheer curtains are sometimes referred to as "privacy curtains" in reference to their screening abilities; during the day most sheer fabrics will allow people inside the home to see the outside view while preventing people outside the home from seeing directly into the home. Due to the loose weave in sheer fabrics, these types of curtains offer very little in the way of heat insulation. Uncoated fabrics provide the next level of heat insulation and light absorption. Uncoated fabrics constitute the vast majority of fabrics used in curtains, and are composed of a tightly woven fabric, most typically a cotton/polyester blend, which is mostly opaque when viewed in ambient light. Uncoated fabrics provide a reasonable level of heat insulation due to their tight weaves, but are too thin to completely absorb strong light. As a result, when curtains made from uncoated fabrics are closed in an attempt to block out direct sunlight, light will still be visible through the curtain because its textiles are shiny. Coated fabrics consist of a standard uncoated fabric with an opaque rubber backing applied