Airing is the practice of hanging or laying out articles and exposing them to air, and sometimes heat and light. This practice is commonly used to dry many types of fabric. One of the most common methods of drying using airing is the clothesline. It consists of a thin wire from which clothing pieces and bedsheets (among others) are hung, using pegs or simply laying the article over the line.

Reasons

Air contains

water vapour (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous ph ...

; warm air can hold more water than cold air. If the temperature of air drops past its dew point, the water will condense out. The

dew point The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will c ...

is the point where the

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

reaches 100%, and the air becomes

supersaturated In physical chemistry, supersaturation occurs with a solution when the concentration of a solute exceeds the concentration specified by the value of solubility at equilibrium. Most commonly the term is applied to a solution of a solid in a liq ...

with water. If water condenses on pieces of equipment, it can cause rot, mould, mildew, and other deterioration. To prevent this, they are brought out in the open, and undersaturated air is circulated around them to dry them out. Some extant mildew can be killed by airing for several hours before vacuuming the cloth. In a building with forced-air heating, the air is brought in from the outside and warmed, so the indoor

is lowered. In cold weather, the relative humidity inside such a building will be very dry, and airing will not be as important. In warmer climates where heating is less-used, condensation is more likely to be a problem. As exhaled breath is at about 100% humidity, breathing in a room will encourage condensation. A human body heats and humidifies clothing it is wearing. Airing clothing after wearing dries it out again. Airing is used to reduce smells and allow clothing to be washed less frequently. Reduced microbial growth aside, a common source of smells is

volatile organic compounds Volatile organic compounds (VOCs) are organic compounds that have a high vapour pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the surrounding air, ...

. As they are volatile, they will tend to evaporate into the air when articles are aired. Airing outdoors is best done when the outdoor humidity is lower, often 1000–1500, midmorning to midafternoon. Airing for a few hours will prolong the life of fabric, but airing for too long in strong light can damage it.

Equipment

Clothing is often hung to air in a clothesline or

clotheshorse The term 'clothes horse' is used to refer to a portable frame upon which wet laundry is hung to dry by evaporation. The frame is usually made of wood, metal or plastic. It is a cheap low-tech piece of laundry equipment, as opposed to a clothes ...

, outdoors in dry weather, and indoors in wet. An

overhead clothes airer An overhead clothes airer, also known variously as a ceiling clothes airer, laundry airer, pulley airer, laundry rack, laundry pulley, or a Sheila Maid, is a ceiling-mounted mechanism to dry clothes. In the North of England it is often known as a ...

may be used to save space. Delicate textiles are aired lying flat, in dim or shaded areas, to avoid fading the colours or weakening the fibers. A plastic sheet covered with a clean sheet, laid outdoors in the shade, can be used to air delicate items that can't be hung. A drying cover, a thin, dark-coloured, breathable cloth, is sometimes used to protect articles from the sun while heating and drying them in the sun. File:Star of India bos'n's locker 4.JPG, A hanging locker in a 1863 ship, for airing lines... File:Star of India bos'n's locker 7.JPG, ...a wooden

grating A grating is any regularly spaced collection of essentially identical, parallel, elongated elements. Gratings usually consist of a single set of elongated elements, but can consist of two sets, in which case the second set is usually perpendicu ...

overhead allows air circulation. File:Elektrischer Schlauchtrockenschrank, Ziegler (DFM).JPG, A drying cabinet for firefighting hoses File:Futon dryer 1.JPG, An electric

futon dryer A is an electric device that warms and dries a Japanese ''futon'' by forcing warm air through it. Mechanism A ''futon'' dryer works by drawing in air with an electric fan and heating it, and then forcing it into a large cloth pouch. The pouch ...

airs a futon in-situ File:TS 30.jpg, A small electrically heated drying cabinet A external heating source allows items to be aired inside even in damp weather, but costs energy, especially if the hot air leaves too rapidly, before absorbing much moisture. A drying cabinet heats a confined space in which items are hung, or shelved on slatted shelves, so the air can circulate; the leakiness of the cabinet can usually be adjusted. Aboard ship, a heated hanging locker fills a similar role. An airing cupboard often uses

waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utilit ...

from an appliance (such as a water heater) to dry items on rods or slatted shelves. In climates where indoor humidity tends to rise too high and promote mould, airing cupboards may have separate ventilation.

Items

Western bedding may be aired for an hour or more after waking, by throwing the covers back or hanging them over the foot of the bed and/or a chair, to reduce mould, mites, and stale smells., a
quoted here
Futons get musty, mouldy, and infested by mites if not aired regularly. The frequency of airing needed depends on the type of futon. Traditionally they are aired by hanging outside, but where this is not possible a

is used. Airing them also fluffs them up, making them more comfortable to sleep on. In the Arctic, furs are aired outside in good weather, especially in spring.

References

{{reflist Humidity and hygrometry Microbial growth and nutrition Textiles Domestic life Medical hygiene