Protection against the sun
The openness factor of a sunscreen is the relative area of openings to fibers in the fabric it is made of, which affect the amount of light that is transmitted through the sunscreen. Sunlight come in three types: visible (detected by human eyes), UV (detrimental to our health) and IR light (heat).
Other light-related properties of sunscreens include glare control, night privacy, visual contact with the outside and daylight utilization. These are all affected by the color, weave, contrast and composition of the sunscreen fabric.