Therm-a-Rest
Encyclopedia
Camping
Camping is an outdoor recreational activity. The participants leave urban areas, their home region, or civilization and enjoy nature while spending one or several nights outdoors, usually at a campsite. Camping may involve the use of a tent, caravan, motorhome, cabin, a primitive structure, or no...
mattress
Mattress
A mattress is a manufactured product to sleep or lie on, consisting of resilient materials and covered with an outer fabric or ticking. In the developed world it is typically part of a bed set and is placed upon a foundation....
es. They were invented in the early 1970s by two former Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
engineers, who were avid backpackers
Backpacking (wilderness)
Backpacking combines the activities of hiking and camping for an overnight stay in backcountry wilderness...
. They named their company Cascade Designs
Cascade Designs
Cascade Designs is an American company specializing in outdoor recreation products. It is located in Seattle, Washington, and was founded in 1972 by two former Boeing engineers, who were avid backpackers...
.
A Therm-a-Rest air mattress
Air mattress
An air mattress is an inflatable mattress/sleeping pad. Due to its buoyancy, it is also often used as a water toy/flotation device, and in UK is termed as a lilo .-For sleeping:...
consists of an airtight nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
fabric envelope filled with a sheet of low density, open-cell polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
foam. When a valve is opened, the foam expands and draws air into the mattress. When the mattress has fully inflated, the user simply closes the valve. To increase firmness, a few breaths of air can be blown into the mattress. To pack the mattress, the valve is opened and it is rolled up tightly to force the air out, whereupon the valve is closed to prevent re-inflation. There is a slight weight penalty in such mattresses compared to non-inflatable pads, but Therm-a-Rest does sell a line of easily compacted non inflatable pads at a much lower price. Open-cell inflatable pads can provide insulation from cold and hard surfaces more efficiently than non inflatable pads. Therm-a-Rest also offer mummy bags, sleeping bags, and seating.
Similar mattresses are now available from competitors.