12.1. Purpose and properties of plaster used in the restoration

Plaster is a finishing layer applied on the surfaces of various structures and elements of the building (walls, partitions, ceilings, etc.).

The purpose of plastering works is as follows:

- align all the irregularities on the surface of the walls and ceilings;

- to carry out the architectural and artistic design of the facade of the building and its interior decoration;

- protect the walls from harmful atmospheric influences.

All types of plaster are divided into monolithic (“wet”) and dry. Monolithic plaster is created by applying a plaster solution to the surface to be treated, dry plaster is applied to the surface to be treated with facing sheets and plates.

The advantage of monolithic plaster is a continuous connection with the surface to be plastered, at which the gaps existing in the structure are closed and gaps between the structure and the plaster are not formed, ensuring seamlessness, the ability to create a surface of any texture and its application in wet rooms. The drawbacks of monolithic plaster are the large labor intensity of implementation, the long period of hardening and drying of the solution.

Dry plaster is less labor intensive; its implementation is not associated with the loss of time for hardening and drying. However, dry plaster is applicable only for finishing the internal surfaces of buildings in rooms with dry and normal humidity conditions.

Monolithic plasters according to their purpose are classified into ordinary and decorative.

Ordinary plasters using lime, cement, gypsum, lime-cement and lime-gypsum solutions are used for interior and exterior (excluding gypsum solutions) of building finishes.

Color pigments are added to decorative plasters, which make the face layer decorative. These plasters are mainly used to finish the facades of buildings.

Ordinary plaster on the quality of finishing is divided into simple, improved and high quality.

Simple plaster is performed in areas where no thorough surface finishing is required. It consists of two layers - spray and soil and is used to smooth the irregularities of building structures. Cover coat is not applied, but rubbed over the surface of the soil.

Improved plaster is usually used for finishing living quarters, as well as for plastering facades of buildings.

High-quality plaster is used in buildings, to the finishing of which they have increased requirements. Such a plaster consists of a layer of spray, one or several layers of soil in order to obtain strictly vertical or horizontal planes, and a covering. Carry out plaster with preliminary fixing of surfaces and installation of beacons.

There is the concept of "clothing buildings." The clothes of the building can be made of natural materials, for example, granite cladding, cladding of ceramic and other materials and lime-sand mortar - plaster. Purpose of plaster, as well as usual clothes, esthetic and protective.

It must protect the walls from the external environment. The destruction of a two-layer plaster-wall enclosing structure is mainly due to the incompatibility of these materials. Materials can be called compatible if, when exposed to external influences, they have the same or similar properties and do not destroy each other. Compatibility of materials in this case depends on the thermal coefficient of linear expansion of the clothes and the wall, on their gas, vapor permeability and water resistance.

The ability of materials to change dimensions with temperature changes is characterized by their thermal coefficient of linear expansion. The thermal coefficient of linear expansion shows which part of the original length the length of the material element changes when the temperature changes by 1 C. Even with minor temperature changes, due to the difference in the very small deformations of the wall and plaster materials, shearing forces appear on the contact surface between them. With prolonged multiple temperature changes, the materials "get tired" and collapse. Fatigue of materials call their property to collapse due to repeated impacts under loads or deformations smaller than the limit ones. At the same time less durable material is destroyed. The values ​​of the thermal coefficient of linear expansion are presented in Table 12.1.

Table 12.1.

The values ​​of thermal coefficient of linear expansion

Bricklaying (old brick)	5x10
Lime-sand plaster (quartz sand)	8x10
Cement-sand plaster (quartz sand)	10x10
Lime mortar with ground limestone filler	5x10

The strength of materials is affected by water resistance. Water resistance is the ability of materials to maintain strength at saturation with water and is characterized by a softening factor less than one.

Gas permeability is the ability of materials with a pressure difference on its surfaces to pass gas through its thickness. By analogy, this definition holds true for vapor-air mixture. Brickwork and plaster mortar - porous materials containing both closed and unclosed - interconnected - pores. They are filled with air, which always contains water vapor.

Such moisture is called condensation. When the outside air temperature decreases, the outside wall temperature becomes lower than the inside. The water vapor pressure is higher, the higher the temperature in this area of ​​the wall. This means that the water vapor pressure in the layers closer to the inner surface is higher than in the outer ones. Due to the pressure difference, the vapors move to the outer surface. If the vapor permeability of clothing is lower than the walls, water vapor accumulates in it along the surface of their contact.

When the temperature decreases, the pores are filled with condensate. At negative temperatures, water freezes and breaks the wall material, forming microcracks. These microcracks subsequently also fill with water and even more destroy the brick. A brick is not an absolutely waterproof material, and if clothing is more waterproof (such as a cement-sand mortar) than a brick, then its strength decreases as a result. This contributes to its destruction. As a result, the plaster falls off along with fragments of brick. The same way is the destruction of the facing of granite, ceramics and other poorly permeable materials, if they are not reinforced "on departure". If the clothing material is more permeable than the wall material, then the vapor-air mixture is brought out.

In addition, there are drip- liquid moisturizing. It takes place in case of rain and strong crosswind, in case of damage to drainpipes and openings of plums, in case of capillary suction of groundwater due to the absence of waterproofing between the foundation and walls, in case of leaks, etc.

With capillary moistening, the plaster is impregnated with water and destroyed during repeated freezing and thawing. The wall remains unharmed. It follows from the above that the outer clothing of a building must not only protect the wall from external drip-liquid moisture and temperature changes, but also remove and evaporate condensation moisture, like a horse's skin, and therefore must have good gas and vapor permeability. In this regard, it seems appropriate to dwell on the so-called "sanitizing plaster".

Often you can find words such as "water-removing plaster" or "plaster pull and evaporate all the moisture." Evaporate, they, of course, evaporate, like any porous material, but due to what they “pull” it is not entirely clear. After all, the movement of vapor-air mixture in a brick can occur only as a result of the pressure difference, as in any material with open pores. If there is no pressure difference, then according to the laws of physics and the movement of the vapor-air mixture either. If we are talking about drip-liquid moisture, for example, about capillary suction of groundwater, then the height of this moisture, as is known, does not exceed 1.5-1.6 meters. Then the plaster should work as a pump, pumping water from the soil to the surface of the clothes and then "evaporating it faster than it arrives." It is not easy to imagine, especially if the humidity of the outside air is high. In the brochures it is difficult to find all the data on these properties of sanitizing plasters, as well as on the properties of sanitizing plasters that affect the compatibility of materials of clothing and the wall.

In any case, both sanitizing and ordinary plasters are protective and ultimately must collapse themselves, but retain the bearing walls.

Cement-sand and lime-cement mortars have a low permeability and therefore unsuitable as exterior clothing of buildings.

The use of complex lime-cement-sand solutions, as has been established, is advisable, first of all, in masonry mortars.

Indoors temperature drops less than outside, but also takes place. Consider the vault plastered with cement-sand mortar. Its temperature changes in two times more than the brickwork. With repeated, small changes in temperature in places (as determined by tapping or opening), the mortar is peeled off from the masonry even with small spans. Over time, the area of ​​detachment increases, but the solution keeps itself at the expense of its rigidity and due to partial adhesion to the masonry. At the same time it is covered with cracks. Then, as delamination and cracking occur, plaster pieces fall out. Part of the non-peeling solution is kept on the wall. Such a character of destruction was observed on cylindrical arches with spans of about 4 m.

Lime-sand mortars are more compatible with masonry, more plastic, and in the absence of leakage they peel off from the masonry and become covered with cracks over a significantly longer time. Therefore, they are more durable, as evidenced by the monuments of architecture and painting that have come down to our time. An example of this is the grounds of antiquity, medieval and Renaissance worked under the murals. In some places, in spite of everything, these plasters are preserved in the Orthodox churches of Russia, Serbia, and Bulgaria (See. Reproductions in the monograph by A. Komarov).

At the same time, it is essential that the soils were made multi-layered, with various fillers. Most often in them, except sand, contained crushed marble or shell rock, crushed brick. In addition, organic proteins, for example, cottage cheese - casein, camel milk in Central Asia, goat milk (all this is also casein) and other types of proteins, were sometimes introduced into the mortar mixture for durability and water resistance. Plasticity - the ability to deform without cracks and tears - each layer of multi-layered clothing was different, therefore the occurrence of cracks throughout the entire thickness of the plaster was restrained by the multi-layer construction of the entire solution array. To increase the crack resistance, a small amount of chopped fibers of straw, wool, and flax was sometimes introduced into the solution (at present, crack-resistant cement-sand mortar with fiber segments is called fiber concrete)

In antiquity in many countries, such as Assyria, Babylon, Phenicia, Syria, lime mixed with brick flour was used to prepare waterproof putties in the construction of water pipes and hydraulic structures (A. Komarov). The introduction of such additives increases not only its water resistance. The coefficient of thermal expansion due to the introduction of crushed bricks also decreased in the direction of approaching the masonry. As a result, all this increased the durability of clothing. Fine-dispersed filler in a thin - 2-3 millimeter - outer layer - covering reduced its moisture permeability.

With large crowds of people emit a large amount of warm moist air. It rises to the top, is deposited on the surface of the vaults in the form of condensate. In Orthodox churches, special drip gutters were arranged at the base of the vaults, onto which condensate drained and was removed outside the habitat. This compacted layer - wiped nakryvka - reduced moisture as the entire thickness of the plaster and brickwork, which had a positive effect on the strength of the whole structure.

Decorative plaster. For each type of decorative plasters apply their solution for the preparatory layer. The thickness of the preparatory layer for any type of decorative plaster should be 15-20 mm. This is necessary in order to avoid the formation of efflorescence that violate the uniformity of the coating. The inconsistency in strength and density of the preparatory layers with the covering leads to their delamination. If the covering layer is stronger than the preparatory layer, then during processing it may peel off from the surface.

Depending on the binder used in the solutions, the preparatory layer is kept wet for 6 to 12 days, watering it with water 3-4 times a day. In windy, as well as hot weather, the ground surface should be covered with matting, hessian, sheets of glassine, etc. and systematically moisturize for 4-7 days, lime-cement and lime mortars - at least 2 times a day, cement-lime and cement - at least 3-4 times a day.

The finishing or decorative layer (covering) is applied when the preparatory layers are seized and acquired strength, that is, after 7-10 days. The finishing layer can be ordinary, designed for painting or splashing, and decorative. The plinths must necessarily be plastered with cement mortar, and the surface should be smoothed down very carefully.

Decorative solutions or cover should be applied to pre-moistened preparatory layers, preferably on wooden beacons in the form of rails. The thickness of the covering is 5-20 mm., It depends on the nature of the subsequent surface treatment of the plaster.

Decorative plasters according to the composition of the solutions from which they are made, and the methods of treatment of their surfaces are divided into three types: lime-sand colored, terrazitic and stone-like.

Lime sandy colored plasters imitate sandstone in their appearance. The color of the plaster gives the filler or pigment introduced into the composition of the solution. Solutions for this type of plaster are prepared on the basis of lime and light artsevoy or colored sand with the addition of pigment. To give the solutions greater mechanical strength and water-holding capacity, 10-15% of cement is introduced into them. The compositions of solutions for lime-sand colored plasters (parts by volume) are shown in Table 12.2.

Table 12.2.

The compositions of solutions for lime-sand colored plasters

Invoice color	dough	Components
		cements			pigments
		portland cement	white portland cement	quartz	ocher	chromium oxide
White	one	-	0.1–0.15	3
Gray	one	0.1–0.15	-	3
Yellow	one		0.1–0.15	3	1/20 volume
			-		the lime
Green	one		0.1—0.15	3		Vso volume
						cement

The color solution is applied to the preparatory layer in two or three doses with a thickness of 5 to 15 mm and leveled with scrappers. After setting, it is moistened with water 2-4 once a day, and on sunny hot days they are covered with a wet sacking, bast mat, or other material. An unhardened plastic solution, leveled with a scraper, can be tread with a bristle brush, this creates a texture “under boulders”, and the stiffer the brush, the more abruptly they will be outlined. You can process the surface of pulp with semicircular teeth, sharpened in one direction. Carrying small fish along the surface along the rule, get grooves, the size of which depends on the type of teeth of the small. The decorative effect is also achieved by treating the surface with a stamp or a relief roller.

The decorative texture of the plaster can be added if the covering layer is applied by spraying. Spray performed with a broom, through the mesh or with a brush.

The surface has an aesthetic appearance, in which gravel and rubble are sunk into a fresh finishing layer, and then it is covered with a liquid colored solution.

And finally, the surface can be processed in a combined way (a combination of several methods).

When preparing mortar plasters, when preparing a mortar, ready-made, dry, prefabricated terrazitic mixtures are factory shuttered with water and thoroughly mixed. In table 12.3. The compositions are given (by volume) for terrazitic plasters that can be made at home.

Table 12.3.

Compositions (by volume) for terrazitovye plasters

Colour textures	Components
	cements		lime		Quartz sand	marble		Pigments decorative fillers
	Portland cement	white	dough	fuzz		baby	powder
White	-	one	-	3	-	6	1.5	Mica 0, 1—0.3
White	-	one	2.5		2.5			Sifted gravel fraction 6-10 mm 4.5; mica 0.1
Light gray	one	-	-	2.5	-	9	3	Mica 0, 1
Yellow	-	1.5	-	four	9	four	one	Ochra 1/50 volume of lime; mica 0.1
Red	one	-	3	-	five	-	-	Red iron 1/30 volume of cement; mica 0, 1

Terrazitovye plaster perform after the preparatory layer hardens over the entire surface. It is necessary to apply the finishing layer in one step on an area bounded by rusties or any other elements, pilasters, window openings, etc.

The solution is applied to the surface in the usual way in two or three steps, depending on the thickness of the covering layer, and leveled with a scraper. После этого штукатурке дают просохнуть в течение примерно 24 ч. (в зависимости от температуры воздуха) до такого состояния, когда верхний слой при затирке начинает осыпаться. Затем приступают к окончательной отделке оштукатуриваемой поверхности – циклевке. Для этого используют цикли и специальную терку – доску размером 100x150 мм и толщиной 20-25 мм, в которую в шахматном порядке на расстоянии 15 мм друг от друга забиты гвозди, выступающие на 10-15 мм. Циклей или теркой сверху вниз проходят по поверхности лицевого слоя, в результате чего образуются небольшие углубления от высыпающейся крошки и отдельных участков раствора.

После циклевания поверхность очищают мягким травяным веником или кистью от засевших в порах штукатурки всякого рода загрязнений и в течение 3-4 дней смачивают водой (один раз в день). Терразитовую штукатурку делают сплошной по всей поверхности или с рустами.

Для достижения большего декоративного эффекта при оштукатуривании оконных и дверных откосов по периметру проемов на фасаде делают рамки из раствора толщиной 20-25 мм, которые затем окрашивают в белый (светлый) цвет.

Камневидные штукатурки имитируют бучардированную фактуру гранита, мрамора и других материалов. Одной из наиболее распространенных является штукатурка «под гранит», которая в течение долгих лет сохраняет свои первоначальные декоративные свойства.

Растворы для камневидных штукатурок отличаются тем, что содержат в качестве заполнителя крошку естественных каменных материалов, имитируя тем самым естественные камни.

Штукатурка – это композиционный материал, состоящий из получаемого искусственным путем известкового камня и мелкого наполнителя, чаще всего кварцевого песка. Химический состав известкового камня очень близок к химическому составу природного каменного материала – известняка СаСОз.

В природном известняке, как правило, содержится большое количество примесей. Примеси влияют на свойство получаемого из него известкового камня. Различают воздушную и гидравлическую извести. Гидравлическая известь может твердеть в воде. Сначала рассмотрим твердеющую только на воздухе воздушную известь.

Воздушной известью называется не доведенный до спекания продукт обжига карбоната кальция (известняки, мрамора). Меньше всего примесей в белом мраморе. Процентное содержание СаСОз немного меньше 100%. Известь, содержащая более 5% и более 10% MgСОз, называется магнезиальной и условно магнезиальной.

Штукатурку получают следующим образом. Сначала обжигают природный известняк. При обжиге известняк разлагается, существенно (до 44%) уменьшаясь в весе. Из него выделяется углекислый газ СО . Остается окись кальция СаО. Это воздушная негашеная известь. Она называется кипелкой, комовой известью. In the XIX century. и ранее ее называли едкой, жгучей, живой известью. Тонко измельченная негашеная известь называется порошкообразной негашеной известью, молотой кипелкой. При обжиге получается некоторое количество обожженного при более высоких температурах спекшегося материала. Эту часть продукта обжига называют пережогом. Его свойства отличаются от остальной обожженной при требуемой температуре части известняка. Кроме того, при обжиге какая-то часть обожженного материала оказывается недожженной. Она называется недожогом, и ее свойства также отличаются от качественного материала. Существенно, что качественно обожженная известь легче, чем неразложившийся при обжиге недожог и спекшийся пережог.

Air lime with CaO content of more than 90% is traditionally called fatty lime . Lime with a large number of impurities is called lean . Next lime extinguish, connecting it with water.

Currently, there are two ways of slaking lime: dry and wet.

And in fact, and in another case, it turns out the hydrate of calcium oxide - hydrated lime Ca (OH) - slaked lime. As a result of quenching by the dry method, powder is obtained . In this case, calcium oxide CaO is poured with the amount of water needed for the quenching reaction. With an insufficient amount of water, lime “burns”, and “dead” lime is produced. It needs to be burned again. Therefore, when quenching by the dry method, take the amount of water, a little more than the calculated. Fluff is used mainly to obtain dry mixtures that are widespread at present.

Wet quenching is called quenching in "dough." In this case, a large amount of water is taken to extinguish the boil. Currently, when the ratio of lime to water is 1: 3 - 1: 4, the resulting composition is called "dough", and at a ratio of 1: 8 - 1: 10 - "milk".

Fluff is different from the wet lime slaked. It is established that the amount of lime dough obtained by directly quenching the boil in the dough is greater than the volume of the lime dough obtained by blanking the boil in the fluff and then mixing it into the dough, and that these volumes are related to each other as 5: 3. The fluff has a particle diameter of approximately 6 microns. When damping by the wet method (in "milk"), the diameter of these particles is 1 micron.

The specific surface for the above particle sizes for fluff is about 4000 cm. on 1 g, and for wet lime - about 20,000 cm 1 g. Therefore, the lime slaked in the dough interacts more fully (with a larger surface) with the filler and reacts when it hardens. Slaked lime in a slightly damp (so that air enters) environment interacts with carbon dioxide. As a result of the reaction, the same compound is formed as the initial product, the limestone, CaCO . This process is called carbonization.

12. 1

It was noticed that if you put small solid aggregate into the dough, for example, quartz sand, you get a more durable composite than solidified clean calcareous dough. This is due to the fact that there is an accretion of more durable grains of sand than limestone with hardening dough. With a strong increase in the hardened mortar, it can be seen that the surface of the sand grains as a result of merging with the lime dough is eaten away. A mixture of lime paste with fine aggregate is called a mortar mixture, and the hardened mortar mixture is called a mortar. The hardening compound (in this case, the lime paste) is called a binder, and the aggregate is inert.

Since carbon dioxide necessary for carbonization is contained in the air, the hardening of the mortar mixture on the air lime occurs from the outer surface of the plaster. After the formation of a thin, hardened layer of limestone and aggregate on the surface of the solution, the flow of carbon dioxide inside the mortar mixture occurs slowly. Therefore, the hardening of the solution is also slow - months and years.

At the end of the XIX century. in the laboratory of the Russian railways, it was found that carbon dioxide from the air penetrates deeper into the masonry on lime mortar by no more than 7 inches (for the unlimited long term - authors ' note ). Hardening releases water. This means that hardening lime mortar is always raw. In old buildings with brick masonry on a lime mortar in the thickness of the walls, there were always left through channels through which air (carbon dioxide necessary for hardening) flowed in, and walls were dried out.

Such channels are preserved, for example, in the Institute. I.E. Repin. These channels have access to the corridors and rooms of the institute and are equipped with metal doors.

During repair, restoration, reconstruction of old objects, sometimes these channels are filled with a solution. As a rule, at the same time in the walls there is a fungus (mold), to get rid of which is almost impossible or very difficult. Therefore, the filling of channels in the thickness of the walls is unacceptable. It is known that 80% of the old housing stock is affected by a fungus. These lesions not only destroy the bearing structures of buildings until collapse, but also cause disease in humans. As a result of diseases, deaths were recorded. Such damage to the walls, not least caused by the silence of the brownies and ventilation ducts.

Hydraulic lime is a product of moderate roasting of clay (over 8% of clay impurities) and dolomitic limestone. A distinctive feature of hydraulic lime is its ability to harden in water. When slaked, hydraulic lime also increases in volume.

The active component of such lime are free calcium oxide and magnesium oxide. Their presence is due to the quenching process. Some of these oxides are associated with aluminum oxides — CaOAl. O and silicon - 2CaO SiO . These compounds harden in water. In the XIX century. distinguished weakly hydraulic, mid-hydraulic, highly hydraulic lime. A solution of weakly hydraulic lime hardens slowly and forms a fragile stone. The solution of highly hydraulic lime hardens faster and forms a more durable stone. For example, a solution of highly hydraulic lime begins to harden after 2-4 days and after six months it becomes strong, like limestone.

These solutions harden over the entire array evenly, and not just from the surface, as "air". It is necessary to apply hydraulic lime immediately after quenching because it hardens and without access of air. GOST distinguishes only weak and highly hydraulic lime, depending on the strength after 28 days.

In accordance with the reference literature, solutions with hydraulic lime are more durable, more rigid. They were used mainly in conditions of high humidity. At present, such solutions in the form of gartsovok - mixtures of quicklime and sand - are widely used for mass construction.

If you add to the solution of air lime certain natural volcanic origin or artificial additives, called hydraulic, you can get a solution with hydraulic properties.

In the XIX century. Vika’s engineer found that the best artificial hydraulic additive is obtained from pure calcined at a temperature of 700-800 With clay. In the absence of such, it is better to use unburned - scarlet brick. Hydraulic additives, among other things, contain a rather large percentage of amorphous silica SiO. . In contrast to crystalline silica, amorphous silica, having an irregular crystal lattice, is active, that is, it easily reacts with other elements. As a result, hardening compounds in water are formed and crystallization of the binders throughout the entire thickness of the clothing wall occurs. In Russia, crushed bricks or tiles were called "cements". Tsemyanka was introduced into the air lime solution, so that the plaster was more compatible with thermal expansion masonry, such as a hardening accelerator, to increase strength and weather resistance.

All limes are classified by quenching speed. This is the time from the moment of contact of the surface of the burnt limestone with water until the beginning of quenching, when the pieces begin to sprinkle from the surface and begin to crumble into smaller pieces. GOST subdivides quicklime into quick-extinguishing limestone - no more than 8 minutes, medium-lasting no more than 25 minutes, slow-extinguishing - more than 25 minutes. Here, only quicklime lime is considered.

It is important that the burnout of any news is extinguished for a very long time - for many years. It is also significant that the volume mass of a well-polluted material is less than that of underburning and burn-through, and that when quenching “into the dough” the size of the particles extinguished is much less than that of underburning and burn-through.

The quality of the plaster depends on many factors and, above all, on how well the lime is quenched.

First, we consider the method of damping air lime of old masters - masters of antiquity. White marble was burned onto lime (CaCO3 content is about 98%). They burned "good" (without underburns) extinguished with excess water (see the wet method). Then a film of calcium carbonate was removed from the surface, the water was changed, it was thoroughly mixed for a long time (up to three years). This is the Roman mode of extinction.

According to the Greek method, in addition to mixing, the dough was “killed by pestles” (crushed by special logs). According to some data (XV century), the lime was “washed” and processed for 3 months, according to others (XVI century) - for 4-6 months, according to other data (XVI century) - from 6-2 months, another method (XVI-XVII centuries) - 2.5-3 years. At the same time, it was believed that “emaciated” lime, that is, lime gets rid of excessive “sharpness and heat”.

Let's try to figure it all out. As a result of all technological operations, it is required to obtain the maximum amount of pure (without impurities) hydrated lime Ca (OH) which, interacting with carbon dioxide, forms a calcareous stone fastening the aggregate. All other non-hardening (including non-extinguished particles of CaO) substances are either harmful or useless.

There is lump lime. It must be repaid in such a way as to produce as much “useful” binder as possible and as few “harmful impurities” as possible. For this, pieces of CaO are poured with excess water and mixed. The resulting hydrated lime is partially dissolved in water. Solubility is 0.13%. This solution on the surface of the water, reacting with carbon dioxide in the air, forms a transparent, slightly whitish, thin-ice film of calcium carbonate CaCO3. It is known from the theory of hardening of lime that hydration (quenching) of CaO particles occurs from the surface. Ca (OH) Molecules form a layer on their surface that prevents water from penetrating into the middle of the CaO particles. Under normal conditions, the hydration process lasts about three years. By mixing and kneading the dough, they destroy the layer preventing hydration and achieve a more complete quenching of CaO in a shorter period. By removing the film and "washing" the lime, reduce the concentration of Ca (OH) solution that contributes to its dissolution from the surface of the CaO grains and the further process of hydration, that is, more complete quenching. The term “sharpness” is most likely understood as “causticity”, “burningness” of quicklime. The heat released during the quenching is apparently the very “heat” that is “disposed of”. The outstanding part of CaO from the surface can be washed out with water, inside the plaster layer, when extinguished, it increases in volume and destroys the calcareous stone and therefore does not form a durable composite.

In Russia, the lime that was extinguished for a long time was called a "seawoman."

This was followed by the next stage of the test preparation. It was necessary to get rid of the harmful particles of burnout. In the hardened solution, the quenching particles of burnout over the years increase in volume and deform the plaster. On its surface there are small swellings, which are called "dutik". They are destroyed, and in their place there are small depressions in the shell. Such an explanation is given in the plastering literature.

In the admonition compiled by hieromonk and painter Dionysius Fournoragrafiot from Athos at the beginning of the 16th century, b