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In
camping Camping is an outdoor activity Outdoor recreation or outdoor activity refers to recreation Recreation is an activity of leisure Leisure has often been defined as a quality of experience or as free time. Free time is time spent away f ...
, a ground pad, sleeping pad, thermal pad, sleeping mat, or roll mat is lightweight pad, common among
hikers Hiking is a long, vigorous walk Walking (also known as ambulation) is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined by an 'inverted pendu ...

hikers
, backpackers and budget travelers, often used in conjunction with a
sleeping bag A sleeping bag is an insulated covering for a person, essentially a lightweight quilt that can be closed with a zipper A zipper, zip, fly, or zip fastener, formerly known as a clasp locker, is a commonly used device for binding the edges ...
. Its purpose is to provide padding and
thermal A thermal column (or thermal) is a column of rising air The atmosphere of Earth is the layer of gas Gas is one of the four fundamental states of matter In physics Physics is the natural science that studies matter, its ...
insulation. All types currently available use air as their primary form of insulation. In its simplest form a sleeping pad consists of a foam-like material that is about half a centimeter thick (about a quarter of an inch). The dimensions of the pad are usually about the same length as a
sleeping bag A sleeping bag is an insulated covering for a person, essentially a lightweight quilt that can be closed with a zipper A zipper, zip, fly, or zip fastener, formerly known as a clasp locker, is a commonly used device for binding the edges ...
and a little wider. Slight variations in design can be found, such as rippling in the foam, but these do not significantly affect the pad's thermal properties. A common misconception is that the pads are primarily for creating a more comfortable sleeping or sitting area. Instead, the primary purpose of the pad is to prevent the loss of
body heat ''Body Heat'' is a 1981 American neo-noir Neo-noir is a revival of film noir Film noir (; ) is a cinematic term used primarily to describe stylish Hollywood Hollywood is a neighborhood A neighbourhood (British English Br ...
into the ground while sleeping. The materials used are typically filled with air pockets, slowing down the
conduction of heat
conduction of heat
through the pad, as air is one of the best (and cheapest)
insulators Insulator may refer to: * Insulator (electricity) An electrical insulator is a material in which the electron does not flow freely or the atom of the insulator have tightly bound electrons whose internal electric charge Electric charge is t ...

insulators
.


Types


Manually inflated

Closely related to the
air mattress An air mattress is an inflatable s are the most common type of inflatable. An inflatable is an object that can be inflated with a gas, usually with air File:Atmosphere gas proportions.svg, Composition of Earth's atmosphere by volume, excludi ...
, a pad of this type requires an external pressure source to inflate, typically in the form of a pump or by blowing orally. Convection of the air inside the mattress reduces the amount of insulation it provides. More complicated mattresses reduce convection by partitioning the internal cavities, or by filling the cavities with material to trap the air such as
down feathers The down of bird Birds are a group of warm-blooded vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological k ...
or synthetic insulation. Manually inflated pads have the advantage of offering good thickness and a great deal of comfort while being lightweight and able to pack to a small size.


Self-inflating

An extension on the conventional manually inflated mattress, this type is capable of self-inflation due to the open-cell foam that fills the internal cavity. For many years this design was protected by various patents held by Cascade Designs and they were an unusual and premium item. But since these patents expired many other manufacturers are now producing this type of mattress and they are now commonplace. These mattresses are lightweight and pack to a small size, which make them popular amongst hikers and campers.


Foam

Closed-cell
foam Foam is an object formed by trapping pockets of gas Gas is one of the four fundamental states of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Moti ...

foam
is used to produce mats that can be used without requiring any inflation. Closed-cell foam pads are lighter and more durable than their self-inflating counterparts, as they are constructed of fewer materials and not susceptible to damage from accidental puncture. Many may also be trimmed to size should the user choose to do so. However, they are generally not as comfortable as manually inflated and self-inflating mats because they are thinner, and may also take up more space in a pack, depending on the materials used. Variations include textured or shaped foam to increase the unrolled volume and/or change the stiffness of the mattress. This can also be used to trap the air within ridges or an egg-carton type of texture. Open-cell foam, although comfortable, is rarely used in the outdoors due to its ability to absorb water (like a sponge) and its air cells are crushed in use reducing its insulation capacity.


Insulation / ratings

A sleeping pads's warmth is characterized by R-value. But unlike sleeping bags'
EN 13537 EN 13537 (or EN13537) is a List of EN standards, European standard designed to standardize the temperature ratings on sleeping bags manufactured and/or sold in Europe. As of 1 January 2005 a European Committee for Standardization, CEN criterion cam ...
test standard and widely accepted recommendations, sleeping pad R-values lacks a simple mapping and label for 'how much warmth' a consumer should expect. Combining various standards and various authors' research, an approximate R-value to temperature chart follows: Same as
EN 13537 EN 13537 (or EN13537) is a List of EN standards, European standard designed to standardize the temperature ratings on sleeping bags manufactured and/or sold in Europe. As of 1 January 2005 a European Committee for Standardization, CEN criterion cam ...
, a "standard man" is assumed to be 25 years old, with a height of 1.73 m and a weight of 73 kg; a "standard woman" is assumed to be 25 years old, with a height of 1.60 m and a weight of 60 kg. The sleeping bag and pad system (above, below, and sides) should provide the same insulation value all around a person, but cost, size, weight, comfort, and lack-of-knowledge often lead persons to reduce the R-value to below their personal 'recommended R-value'. Since the pad and bag work together, a 'warmer' bag can compensate the a 'thin' pad and a 'thick pad' for a 'cold' bag. Highly heat-conductive surfaces (e.g.
concrete Concrete is a composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material Material is a substance Substance may refer to: * Substance (Jainism), a ter ...

concrete
,
granite Granite () is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cool ...

granite
) require more insulation for the same temperature than insulating ground surfaces (e.g.
snow Snow comprises individual ice Ice is water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). ...

snow
, dry moss, loose soil, wood, etc.). More heat is lost downward when sleeping on one's stomach vs sleeping one's side (due to reduced contact area and cooler body parts in contact). Most persons can 'feel the cold ground' at approximately half the 'recommended R-values'. Sleeping pads R-values range from 1 to more than 10. A few category examples follow:


See also

{{Wiktionary, camping mat *
Swag (bedroll) In Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands ...
*
Yoga mat Yoga mats are specially fabricated mats used to prevent hands and feet slipping during asana practice in modern yoga as exercise. An early variety made of rubber carpet underlay, pioneered by the yoga teacher Angela Farmer in 1982, was called a s ...

Yoga mat


References

Camping equipment Travel gear Mattresses