Steam bath

The original deeply sensual meaning of the term Slavic term couples (from the word pret ^[1] ) is the sensation of internal moist heat, including the animal ^[2] . This ancient fundamental concept has long been largely forgotten (as obsolete) - its fragments are now preserved only occasionally in common folk language: steam hut (that is, warm, heated inside), fresh milk (warm, just from under the cow), steam meat (not chilled fresh), soar (heat your own heat or heat something up to the inside, to sweat), sweat (outgoing steam in the body in the form of sweat). But congratulations "Enjoy Your Bath!" still remembered in everyday life and is carefully preserved as a national humanitarian asset and a distinctive feature of the Russian people, because nowhere else in the world do they congratulate people on a pleasant light steam (internal heat - heat) in a clean cooling body AFTER a steam bath ^[3] .

The steam bath is a special room for hygienic procedures, including the method of warming up the body using hot steam. It differs from other methods of body cleansing by the following parameters:

• washing is carried out in air using limited amounts of warm water (that is, without immersing the body in warm water),
• Washing is performed in special heated bath rooms, creating conditions for the release of sweat on the skin surface.

There is no technically standardized definition of the term steam bath . The above formula expresses the technical essence of the first official humanitarian definition: “A bath in Slovene language means ablution, in its general usage it means a building in which they soar and wash” ^[4] . This definition has been preserved in subsequent official explanatory and encyclopedic dictionaries of the Russian Empire, the Soviet Union and the Russian Federation ^{[5] [6] [7] [8] [9]} . Vocabulary clarification is also essential - in a steam bath (as in one of the types of steam baths) “they bathe and soar not just in dry heat, but in steam” ^[10] .

Warm Wash Methods

Steam baths are subdivided according to the method of washing into sweat, steam and neck baths ^[11] .

Ways of warm washing: a - sweat bath, b - steam bath, in - a step bath, g - a bath, d - a shower

Steam baths were the creation of hot conditions of stay using a small amount of water. In antiquity, steam baths (under different names) were the only possibility of year-round body hygiene, as people learned early to heat the room with fire (fire, stove), but did not know how to get large amounts of warm water for a long time due to the lack of large metal utensils. Later, people learned to heat hot water in the required quantities and to supply it with even individual dwellings (apartments, private households). Thus, with the development of civilization, steam baths began to be replaced by baths and showers that do not require high temperatures in rooms intended for hygiene (due to the immersion of most of the human body in warm water).

Sweat bath

The sweat bath (warming) is different in that the person washes his own sweat - first, in one way or another, it warms up (“soars”) and, sweating (“having pouted”, “soaking”), itching with nails, rubbed with palms, rubbed with a sponge, lashes himself with a broom . The sweating bath is the most ancient (“wild”) method of washing, but preserved at high levels of civilization, in particular, in the early Roman baths, where visitors, sweating after exercise on the sports ground ( gymnasium , palestra ), scraped sweat from the skin along with pollution with special scrapers - strigils in warm rooms with heated floors ( hypocautes ). In the hammams , in particular, in the Turkish baths, they sweat and rub with hair washcloths on a heated stone surface (on the platform chebek-Tashi - “abdominal stool”). A traditional Finnish sauna is also considered to be a sweating bath (“sweat bath”) ^[12] . The ancient Novgorod bathhouse (“movnya)" in the Slavic land ", described in the Chronicle and recognized as" diva "in Kievan Rus, was also sweaty, too, they say, they would flood the wooden baths very much (i.e., cover themselves later) , beat themselves with "young bars" (that is, with brooms) and "do that thing for themselves to bathe" ^[13] . There was no mention of steam and the supply of water to the stones in Letopisi. Yes, and the Greek word "bath" in Novgorod itself in those years, apparently, was not known ^{[14] [15] [16]} . A sweating bath was also a washing in the furnaces of Russian wind stoves in Vladimir-Suzdal Russia ^{[17] [18]} .

Steam bath

Steam bath (steam room) is different in that a person is washed with water condensation, falling in the form of hot dew on the skin from the high-humidity air. High-humidity air ( “steam bath” ) in a steam bath was traditionally obtained by irrigating water on stones heated with fire — the water evaporates and then condenses onto the human body. Although the steam bath (born “steam bath”) has long been known everywhere (for example, the bust ), it was the textbook that became the Russian bath: “A bath (steam bath, Russian bath) is a structure where they wash and soar not just in the dry heat, and in a pair ” ^[19] , where the words“ soar ”and“ in a pair ”actually had different essential meanings.

Steam bath concept

The term “steam” in its historical development over the centuries has consistently acquired various additional meanings, which still leads to semantic confusion, especially in baths. “Steam” (including in the steam bath) eventually began to call not only the internal moist heat, but also the consequences of heating water and moisture (internal water) - invisible eye evaporation (a couple of substances), visible trickles and clouds of mist ( bulk condensate of water vapor in air), “steam bath” as “air saturated with hot water vapor” ^[20] , and subsequently technical (“locomotive”) steam undiluted with air from a steam boiler (pressurized) or from a heater, which was mixed with hot air bath ^[21] .

Step bath

The step bath (washing) is distinguished by the fact that a person is washed with warm water from a small vessel by the method of splashing, drenching and rubbing. Moreover, a person washes the whole body (and not separate parts of the body as during washing and washing out) in the open air in a warm room with warm water disposed in gangs, basins, and troughs. The most vividly the essence of a bathhouse is manifested in a modern everyday example, when, when disconnecting hot water in apartments, they try to wash themselves in a bathroom with a basin of warm water heated on a stove. Everyone knows that if you rinse (or even wipe) your entire body with warm water, it will immediately become cold (due to evaporation of moisture from the skin). This means that in order to wash in these conditions, it is necessary to additionally warm up the bathroom, that is, to turn the bathroom into a steam bath. The step bath was widely used for mass warm washing of people due to the economical consumption of warm water in comparison with showers and baths.

Collective image of a steam bath

All of the above methods of warm washing, including steam baths, baths and showers, are technically self-sufficient ways (although they can be arbitrarily combined together). None of these washing methods will ever disappear from a person’s life and therefore cannot be recognized as an anachronism (a relic of the past). Only specific technical solutions can be morally obsolete, for example, in terms of types of premises (building structures), interior decoration, engineering support, and washing conditions ^[22] . So, since the times of the USSR, citizens, as a rule, innocently rank “bathhouses” (as remnants of the past) all washing facilities that differ from apartment baths and showers. This is due to the irrevocable transition of humanity from the socially-collective nature of household washing (in the baths of the traditional village or communal type) to the individual apartment (intimate). However, a person washing in his private bathroom often rises above the water (or comes out from under the shower) while washing with a washcloth with soap, which actually corresponds to the transition to the traditional bath washing process - to a step bath. Currently, large cities are increasingly faced with problems of water supply (in terms of quantity and quality of water) and drainage. Therefore, in the future, it is possible that the principles of steam baths (water saving) can be returned to the citizens' individual housing, but at a different level of civilization.

Steam bath microclimate

The microclimate of steam baths is significantly different from the usual microclimate of residential premises. So, if, according to Russian standards, the normal temperature of residential premises, bathrooms and shower rooms is normalized at a level of at least 18 ^o C, then in the steam baths the air temperature should be at least 40 ^o C in steam rooms and at least 30 ^o C in the washing compartments ^{[23 ]} , which is supported by the established practice of mass urban construction ^[24] .

Climate regimes

The microclimate of steam baths is determined not only by the temperature of the air, but also by the humidity of the air, which hampers the evaporation of water from wet skin and reduces the cooling of the human body in air. The possibility of evaporation of water (with drying of the skin) stops when the air dew point is equal to the temperature of the skin (remaining unchanged in the bath at about 40 ^o C due to human homeostasis ). This corresponds to an absolute humidity of 50 g / m ³ . In the coordinates “relative air humidity - air temperature” (typical for household meteorological stations), such absolute air humidity corresponds to meteorological regimes (meteorological points, meteorological parameters, meteorological conditions) , depicted graphically in the form of a so-called theoretical (calculated) “homothermal curve” (from the Latin homo "- man," terma "- warm) ^[25] .

Theoretical homothermal curve ^[26] .

Dry weather modes

Dry weather patterns are located under the homotermal curve and are physically different in that water (or sweat) from a person’s skin evaporates (with drying out wet skin and cooling the person’s body). At the same time, the evaporation of water ("sweating") increases with the appearance of air blowing over the body. For example, if the nasopharynx blown with air cools down when inhaling, then this is a dry weather mode of the bath - that is, the so-called dry bath , and perhaps not a steam bath at all, since under these conditions a person with wet skin may become cold, despite to high temperature in the bath. This means that the concepts of dry bath (dry weather mode) and dry air are fundamentally different. In a dry bath, the skin of a person dries, conditionally having a temperature of 40 ^o C. In the dry air (that is, in air with low relative humidity) surfaces that have a temperature equal to that of air dry. Therefore, in a dry bath at air temperatures above 60 ^o C, the skin can both dry and moisten (depending on the specific meteorological parameters in accordance with the homothermal curve) ^[27] .

Wet weather modes

Wet weather patterns are located on the homothermal curve and are physically different in that water (or sweat) does not evaporate from human skin. A person loses the ability to self-thermoregulation, that is, the skin does not dry and the human body does not cool, regardless of the presence of airflow. The wet weather mode is stuffy ("wadded"), because when you inhale the nasopharynx is neither cooled nor heated. Wet weather mode is characterized not by sweating (evaporation of sweat), but by sweating (with accumulation of sweat on the skin followed by trickling down). A person “soars” (heats up and overheats) both due to the heat of the room (hot air and walls), and due to natural internal physiological heat release (about 80 W at rest and more than 290 W during heavy physical work ^{[28] [29]} ) .

Steam weather modes

Steam weather patterns are located above the homotermal curve and are physically different in that hot dew (condensate of water vapor from high-humidity air) falls on the skin, releasing the heat of condensation. In these weather modes, a person can seriously scald, especially when the body is blown with hot ( “steam bath”) . It is these meteorological regimes above the homotermal curve that came to be called “Russians” in urban steam baths (with a brick stove and with a closed heater) when steaming with a broom ^[30] .

Air humidification in a steam bath

To obtain a steam weather mode, it is necessary to evaporate about 50 grams of water per one cubic meter of bath volume. Water is usually poured in portions (the so-called "sacrifices") on a hot stove, but steam weather modes can be obtained by boiling water in a vessel or by evaporating moisture from the walls. The vapor formed during the evaporation of water enters the bath volume and mixes with the air, forming a “steam bath”. Since moist air is lighter than dry air, the “steam bath” rises up and can form a layer of over-humidified heated air in the form of hot “steam cake” near the ceiling. In this case, sweeps with a broom can "scald" the human body. Therefore, in the course of “sacrifices”, the air in the bath is often mixed-averaged (“steam is dispersed” with the destruction of “steam pie”) with a broom, which leads to partial condensation of water vapor on the cold floor with air drying. As a result, the constantly high aerodynamic circulation of air in the bath (due to natural convection at the hot stove or above the stove) does not allow obtaining steam regimes, in particular, in chicken (black) baths and in modern Finnish dry saunas with an open stove ^[31] .

Mixing vapor-air mixtures

Mechanical mixing of two different vapor-air mixtures leads to the formation of new vapor-air mixtures, the temperatures and absolute humidity of which have (approximately) average values ​​from the initial values ​​of meteorological parameters of the mixing mixtures (due to the proximity of mass heat capacities of air and water vapor).

Bath-steam chart. Weather point C is chosen arbitrarily (taking into account the convenience of graphic illustration). Real meteorological parameters C (near the human body) lie in the zone of temperatures less than 100 ^o C and M less than 0.1 kg / kg ^[32] .

This means that in the so-called “bath-steam diagram” (in the coordinates “temperature is the mass fraction of water vapor in the steam-air mixture”), the meteorological parameters of the new vapor-air mixtures (for example, meteorological point “C”) are located (approximately) on a straight line segment (for example, "OB") connecting the original weather points ("O" and "B") of mixing air-steam mixtures. No other values ​​of meteorological parameters can arise in principle at any point of the bath (in the absence of external cooling and dehumidification of mixing air-steam mixtures in the bath).

Scorching steam bath

The scalding bath steam is vapor-air mixtures, characterized in that their microclimatic meteorological points correspond to a saturated steam . So, if 100% (without air) water vapor with a temperature “A” with a temperature of 100 ^o C (for example, from a boiling kettle) is supplied to the air bath with the “O” meteorological point, then a straight line connecting these meteorological points will inevitably intersect saturated steam curve. Thus, spatial zones inevitably arise in the bath volume with vapor-air mixtures corresponding to the supersaturated steam (to the left of the saturated steam curve). This supersaturated (“supercooled”) “steam bath” immediately releases hot dew on human skin, turning into saturated steam. Therefore, such a “steam bath” is burning (scalding), especially in the presence of air movements (for example, from a broom). In particular, when inhaling such a “steam bath” will burn the lips and mouth, without bringing the heat to the nasopharynx. In addition, the appearance of condensate in the bath volume in the form of "steam" (mist, that is, aerosol suspension of small water droplets), which can lead to a sore throat.

Light steam bath

Light steam baths are vapor-air mixtures, characterized in that their microclimatic meteorological points correspond to superheated (unsaturated) steam . So, if 100% (without air) water vapor with a “B” meteorological point with a stove with a temperature of 400 ^o C is fed into the air with the “O” meteorological point, then the segment connecting the straight line never crosses the saturated steam curve. This means that in this case it is impossible to get saturated and supersaturated steam when mixing - “steam puffs” do not arise. The resulting vapor-air mixtures of superheated steam with meteorological point “C” are characterized by the fact that they are first cooled in the human body as an ordinary gas (without vapor condensation), and only when the meteorological point “D” reaches cooling, they acquire the ability to release condensate. Therefore, upon contact with human skin, such vapor-air mixtures, referred to as “light steam bath”, have a mild effect on the skin — they do not burn or scald, but “pinch and tingle”, first of all, the ears. When inhaling, such a “light steam bath” does not burn lips and mouth - the heat of condensation is released in the nasopharynx and even deep in the bronchi, which is popularly known by breathing soft steam “over a hot potato”. In everyday life, there are other everyday ideas about the “light steam bath”, for example, as a not very hot “steam” (for example, while cooling a bath) or about hot air without smoke and intoxication. However, such sensory judgments are not directly related to the physical essence of the steam weather patterns in the steam bath.

Calculated splash-steam diagram ^[33] .

Raw steam bath

Crude steam bath is a vapor-air mixture, characterized in that it contains a spray of water or mist droplets. For example, in the case of explosive evaporation of water (with cotton on hot stones) in steam emissions (in water vapor from the heater), not only hot water vapors are present, but also water splashes. When water splashes into the air bath, it turns out "raw steam bath", in which the spray begins to evaporate, not only moistening the air, but also simultaneously cooling it due to the latent heat of evaporation. For example, in dry Finnish saunas, the air near the ceiling is usually cooled by watering even the very hot stones of the open heater. At the same time, spatial zones with burning “saturated steam” may occur, especially in the near-ceiling areas of the room (in “steam cake”). The degree of influence of splashes on the temperature of the resulting “steam bath” can be estimated from the spray-steam diagram , where the mass concentration of splashes (in the steam ejection from the heater) are located above the calculated Bcr curve, at which the air temperature in the bath decreases and the “burning steam vapor” is formed ".

Draining a wet steam bath

A light steam bath cannot be damp. Therefore, the steam release (water vapor from the heater) is desirable to dry, that is, to separate from the spray. In the technique, splashes of water from steam (in a boiler or steam pipe) are often mechanically separated, for example, with bell-shaped (labyrinth) sprayers before steam is supplied to the working cylinders of the steam engine. In the bathing practice, for the elimination of possible splashes, use is made of closed stoves, where splashes from hot stones fall on the hot walls of the heater and evaporate there. However, steam ejection from closed sauna-stove sauna brick stoves usually has a temperature “with claps” of no more than 150 ^o C, although the heater stones themselves sometimes burn to a red glow (more than 700 ^o C). This indicates the departure of residual amounts of spray through the open door of the heater. Therefore, to get a really light steam bath in a bath, steam emission dried in a closed sauna heater should be additionally overheated to evaporate residual splashes by passing dried steam through a layer of hot stones (heating a drying sauna heater) or through a narrow gap between the heated surfaces in metal bath furnaces.

Physiological perception of the bath microclimate

The microclimate in the bath is designed to create comfortable conditions for washing and soaring - so that it is not too hot or too cold. A person feels the heat in the bath (heat) before the skin and mucous membranes of the respiratory tract.

Portability Time

At high heat fluxes, the skin overheats (with respect to the body) and the skin's nerve receptors signal the danger of burns - first burning the skin, then tingling and tingling, and finally, unbearable pain (with scalding) with a reflex urge to retract. Grabbing the hot handle of the pan, the person immediately realizes how much time he can hold it in his hands. This time that can be tolerated is understood as skin tolerance time ^[34] .

With a decrease in the heat flux, the heat has time to go deep into the body, and the skin does not overheat (as in the case of cooking kebab, when the heat from the coal does not char the outside, but warms up, stews deep into). A person does not feel the heat at all as a small heat flux (less than q _habituation = 200 W / m ² ) - the person “gets used” to them. So, for example, the internal physiological power of heat generation of a person at the level of 100 W (with a surface area of ​​a person of the order of 1 m ² ) is considered commonplace and is felt only with prolonged exposure to warm, steam-proof clothing. However, even with a slow warm-up of the body, the blood can sooner or later "overheat" to 39-41 ^o C and lose the ability to attach oxygen to the lungs. There comes a heat stroke. When the body is heated from above (for example, from a hot ceiling as from the sun), the head overheats, and this heat stroke is called solar (it is typical of modern high-temperature Finnish saunas). The time before the onset of thermal shock is called the time of tolerance by the body, which greatly exceeds the time of tolerance by the skin (except in cases of small heat fluxes of the order of q _habituation , at which they practically compare). This means that a person in a bath can warm up deeply with his whole body only under conditions of moderate heat loads (no more than 500 W / m ² ), otherwise the person is forced to leave the steam bath without warming up, due to the intolerable burning of overheated skin (by analogy with cooking barbecue on the coals).

Extreme heat loads

Tolerance times of about 10 seconds by the skin (and 5 minutes by the body) are perceived by a person in the bath as extreme conditions corresponding to the values ​​of heat fluxes to the skin in excess of 3000 W / m ² . These values ​​significantly exceed the solar heat load on a tropical beach of about 1000 W / m ² , but do not reach the heat loads of scalding and scalding of the order of 10,000 W / m ² (for comparison, wood ignites at a heat load of 14,000 W / m ² ). In official medical photophysiotherapy, heat fluxes to the human body are divided into soft (1-20) W / m ² , medium (20-300) W / m ² and hard (300-5000) W / m ^{2 [35]} . At typical temperatures and humidity of steam baths, the calculated thermal load on a stationary body in still air is about 200-500 W / m ² , which corresponds to heat generation during heavy physical work (with a body tolerance of about an hour or more). When using a bath broom, thermal loads can increase up to 3000 W / m ² (and higher when the hot broom touches the body).

But there are factors that can lead to scalds and burns of the human body:

• Direction of steam emission from the heater directly to the human body.
• Excessively high velocities of body blowing (for example, with sweeps of a broom or hand movements) with hot “steam” with a dew point above 50-55 ^o C (see the thermal-thermal curve), since heating due to condensation of water vapor can become not just extreme, but and unbearable.
• Excessively high temperature of the ceiling and surfaces of stoves, heaters, since the radiant fluxes on the skin can become comparable to a tropical beach level of 1000 W / m ² (and higher up to unbearable), which requires the protection of the body, first of all, to avoid sunstroke. Thus, high-temperature saunas (“dry air” without a mirrored ceiling) unbearably burn a dry body, not so much because of the high air temperature, but because of the high level of heat radiation from the hot ceiling.
• Excessively high temperatures of the shelf surfaces when touched, especially in the case of using high conductive materials (metals, stone).

Features of a warm person

At elevated body temperature, hormones begin to flow into the blood, dilating the peripheral blood vessels (with reddening of the skin) and opening the ducts of the sweat glands with the appearance of so-called profuse sweating (with abundant sweating on the skin). Since the transfer of heat into the body of a person is determined mainly by the circulating blood, the reddened skin (due to the expanded peripheral blood vessels) of a heated person is able to tolerate much greater heat loads than indicated on the graph. Thus, a person is not able to immediately lower cold feet into hot water at a temperature of 38-39 ^o C, but after gradually warming up the feet, such hot water does not seem excessively hot for reddened skin of the feet. Similarly, in a steam bath, a preheated person is able to tolerate skin with increased thermal loads when steaming with a broom and increased temperature drops during cooling after a steam room in an ice-hole. These features of the human body are widely used in steam baths. In particular, it is recommended to warm up with dry skin before extreme sweating with a broom, at least until sweat appears. So, a heated person is physiologically different from an unheated person.

Advantages of washing in a steam bath

Man's steam bath washing has its specific advantages compared with baths and showers. In technical terms, this is a small need for hot water, low cost of construction and its simplicity in autonomous conditions. On the consumer side, it is the convenience of washing, since the person is not so limited in spatial movements, as in the case of apartment baths and showers. Steam bath washing can provide a higher quality of human skin cleaning. The fact is that when washing in baths and showers (even with chemical detergents), salts and fats that have accumulated on the skin from secretions of sweat and sebaceous glands are predominantly removed. But it is also important to remove dead scaly of the stratum corneum, closing the mouths of the duct of the sweat glands and preventing the free flow of sweat with the creation of pressure on the skin receptors with the appearance of dirty skin sensations and desires to scratch. The removal of scales of steamed stratum corneum is carried out mechanically - by scraping with nails, scraping with a scribe, wiping with palms of hands, whipping a broom, combing with brushes, rubbing with washcloths.

The shear force (friction) of the instrument when washing, depending on the amount of water on the skin

It is easy to see that when there is an excess of water in the baths and showers, the instrument of washing cannot lubricate with the layer of water and “slip over the skin” and move the layer of dead scales of the stratum corneum. So, the finger wetted with water easily slides on a palm (wet sliding). But as it dries, the finger begins to feel the friction force - “sticking” to the skin (scuff phenomenon). And then, already with the dried finger, the friction force again decreases (dry slip). Therefore, during warm washing it is important to have a limited amount of water between the washing instrument and the steamed skin. This can be realized when bathing with a washcloth in the air (or, for example, rubbing steamed skin with a dry towel according to the Japanese bath tradition). Therefore, in a bath, when washing with a washcloth, a person sometimes involuntarily rises above the water, that is, switches to a bathing method of washing. These features are also used in cosmetology, where “rough” rubbing of steamed face skin with a napkin cleans better and softer than skin-damaging (in fact, surgical) methods, such as mechanical skin scratching with scrubs (abrasives) or chemical dissolution of the horny layer of the epidermis with fruit acids. When wiping, you can additionally apply solutions of alcohol (colognes, lotions), effectively exfoliating flakes of steamed horny layer.