A sheer or net curtain is one that is made from translucent fabric, such as a loosely woven polyester voile or a cotton lace. 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 the tight weave of the fabric.
However, the fabric itself is typically not thick enough to completely absorb strong light sources. 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.
Coated fabrics consist of a standard uncoated fabric with an opaque rubber backing applied to the rear of the fabric to provide improved light absorption. To create a coated fabric, a liquefied rubber polymer is applied in a single coat to an uncoated fabric and subsequently fused dry by means of a heated roller, in much the same way that a laser printer applies toner to a sheet of paper before fusing it dry.