A top hat, also known as a stove pipe or snoot, is a device used in theatrical lighting to shield the audience’s eyes from the direct source of the light. It is shaped like a top hat with a hole in the top, and the brim being inserted into the gel frame holder on a lighting instrument. The cylinder allows light to pass through but takes away the glint of a lighting instrument facing the audience. It also reduces flare created by the light, which is often useful when the unit is hung near the proscenium or other objects that the designer does not want to light. There are also half-hats or “eyelashes”, which function in a similar manner but have only half the cylinder, and short hats, which are shorter in length. Top hats are manufactured for most modern-day lighting instruments with gel frames of varying sizes.
Research and practical experience with the degradation of roofing membranes over a number of years have shown that heat from the sun is one of the most potent factors that affects durability. High temperatures and large variations, seasonally or daily, at the roofing level are detrimental to the longevity of roof membranes. Reducing the extremes of temperature change will reduce the incidence of damage to membrane systems. Covering membranes with materials that reflect ultraviolet and infrared radiation will reduce damage caused by u/v and heat degradation. White surfaces reflect more than half of the radiation that reaches them, while black surfaces absorb almost all. White or white coated roofing membranes, or white gravel cover would appear to be the best approach to control these problems where membranes must be left exposed to solar radiation.