page_title: Wetsuit
section_title: Insulation
hierarchical_section_title: Wetsuit / Insulation
caption_attribution_description: en:wetsuit, particular
context_page_description: A wetsuit is a garment worn to provide thermal protection while wet. It is usually made of foamed neoprene, and is worn by surfers, divers, windsurfers, canoeists, and others engaged in water sports and other activities in or on water, primarily providing thermal insulation, but also buoyancy and protection from abrasion, ultraviolet exposure and stings from marine organisms. The insulation properties of neoprene foam depend mainly on bubbles of gas enclosed within the material, which reduce its ability to conduct heat. The bubbles also give the wetsuit a low density, providing buoyancy in water.
  Hugh Bradner, a University of California, Berkeley, physicist invented the modern wetsuit in 1952. Wetsuits became available in the mid-1950s and evolved as the relatively fragile foamed neoprene was first backed, and later sandwiched, with thin sheets of tougher material such as nylon or later spandex. Improvements in the way joints in the wetsuit were made by gluing, taping and blindstitching, helped the suit to remain waterproof and reduce flushing, the replacement of water trapped between suit and body by cold water from the outside.
context_section_description: Still water (without currents or convection) conducts heat away from the body by pure thermal diffusion, approximately 20 to 25 times more efficiently than still air. Water has a thermal conductivity of 0.58 Wm⁻¹K⁻¹ while still air has a thermal conductivity of 0.024 Wm⁻¹K⁻¹, so an unprotected person can succumb to hypothermia even in warmish water on a warm day. Wetsuits are made of closed-cell foam neoprene, a synthetic rubber that contains small bubbles of nitrogen gas when made for use as wetsuit material (neoprene may also be manufactured without foaming for many other applications where insulating qualities are not important). Nitrogen, like most gases, has very low thermal conductivity compared to water or to solids, and the small and enclosed nature of the gas bubbles minimizes heat transport through the gas by convection in the same way that cloth fabrics or feathers insulate by reducing convection of enclosed air spaces. The result is that the gas filled cavities restrict heat transfer to mostly conduction, which is partly through bubbles of entrapped gas, thereby greatly reducing heat transfer from the body (or from the layer of warmed water trapped between the body and the wetsuit) to the colder water surrounding the wetsuit.
  Uncompressed foam neoprene has a typical thermal conductivity in the region of 0.054 Wm⁻¹K⁻¹, which produces about twice the heat loss of still air, or one-tenth the loss of water. However at a depth of about 15 metres (50 ft) of water, the thickness of the neoprene will be halved and its conductivity will be increased by about 50%, allowing heat to be lost at three times the rate at the surface.
  A wetsuit must have a snug fit to work efficiently when immersed; too loose a fit, particularly at the openings (wrists, ankles, neck and overlaps) will allow cold water from the outside to enter when the wearer moves. Flexible seals at the suit cuffs aid in preventing heat loss in this fashion. The elasticity of the foamed neoprene and surface textiles allow enough stretch for many people to effectively wear off-the-shelf sizes, but others have to have their suits custom fitted to get a good fit that is not too tight for comfort and safety.
  Foamed neoprene is very buoyant, helping swimmers to stay afloat, and for this reason divers need to carry extra weight based on the volume of their suit to achieve neutral buoyancy near the surface. However, the suit loses thermal protection as the bubbles in the neoprene are compressed at depth Buoyancy is also reduced by compression, and scuba divers can correct this  by inflating the buoyancy compensator.
caption: Semi-dry cuffs use a smooth surface to seal against the skin to reduce flushing.
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