Marble is an extremely necessary and useful stone, and its benefits lie not only in those amazing works of art from Italy and Greece that we admire in museums. The scope of its application is much wider. So much so that it is difficult to imagine what our life would be like without marble.
Marble can be found in the operating room; after all, where all tables and walls must always be perfectly clean, marble slabs are irreplaceable; at the electric station, where control devices are located on huge distribution boards, here again along the walls there are huge boards of marble, impenetrable and non-conductive of electricity; in hospitals and sanatoriums with beautiful, clean marble baths and washbasins with marble slabs; at the tannery, where the most delicate types of leather are rolled using large marble rollers; of course in the subway, as well as theaters, public buildings, with their beautiful marble columns and balustrades, with marble cladding, marble steps and window sills, durable, always clean and not suffering from water, frost or the blows of many thousands of feet; in the beautiful cladding of buildings made of marble or marble granules mixed with cement, and so on - it is simply impossible to list to the end!
Marble is a hard mineral, but at the same time it is soft enough to be sawed with an iron. Pure white, dazzling white; sometimes with a pleasant transparency that resembles the color of human skin; sometimes of variegated beautiful colors - yellow, pink, green, red, black: uniform and clean, non-conductive of electricity, resistant to the destructive effects of water and air, marble is a wonderful material in human hands, and man appreciated it many thousands of years ago.
Anyone who had the opportunity to admire ancient Greek temples made of snow-white marble, or who climbed the winding staircases to the roof of the marble Milan Cathedral - in the midst of fine carvings, columns and decorations carved from stone, or descended the marble steps of the Moscow metro - cannot help but admire this wonderful stone.
In Italy, on the shores of the Mediterranean Sea, near the famous Carrara, there are up to a thousand pieces of snow-white marble. High in the mountains, in wild gorges, white marble rocks imperceptibly merge with the snows of the Apuan Alps. From wild cliffs, with the help of harnessed oxen on rollers, blocks weighing several tons are pulled down. To prevent them from rolling down and crushing anyone, blocks of the same marble are tied to them from behind with chains, which are dragged along the slopes with a roar and slow down the rollers.
Next, the blocks are cut into marble boards in water mills. Then the stone boards are transported by rail to the shores of the Mediterranean Sea; there huge cranes lift planks and blocks and lower them into the holds of large ocean-going steamships. Thus, huge amounts of marble are sent to different parts of the planet every year.
Russia is no less rich in marble - Karelia, the Moscow region, Crimea, the Caucasus, the Urals, Altai, and the Sayan Mountains.
But marble is not eternal: if you look at the old parts of the cladding of St. Isaac's Cathedral-Museum or at the columns of the Marble Palace in St. Petersburg, you can see how much the old pieces have changed, how the corners have been smoothed out, and the size of the decorations has decreased. The air, especially in cities, contains many substances poisonous to marble, and therefore rainwater destroys this stone unusually strongly and quickly.
IN 100 years About 1 mm of marble dissolves, and in 1000 years - a whole centimeter. But this is not enough: the proximity of the sea increases the destruction of marble: salty sea spray is carried inland for many hundreds of kilometers and corrodes the stone even more. The snow is still in effect stronger than rain, as it absorbs even more toxic acids from the air. Water freezing in cracks, thin roots of plants and fungi also accelerate the destruction of marble, and the wind, carrying dust and sand, polishes and erases the soft surface of the stone.
There is nothing eternal in nature. Geological periods of thousands of years, on the one hand, accumulate entire mountains from microscopic grains of sand, and on the other, they destroy and smooth out the solid, immutable rocks of past centuries. The laws of nature are the same, and in the complex geological history of nature, human activity and the eternity of his creations are only a very small, quickly passing minute.
Article based on the book:
Alexander Evgenievich Fersman, Interesting mineralogy.
Products made of stone and ceramics are combined into one general group of materials because the methods of conservation and restoration of them are almost the same, and this, in turn, depends on the related nature of their original materials. This situation, however, requires very serious clarification, otherwise we could destroy quite a few museum items.
The fact is that the concept of “stone” covers such different materials that although in practice we seem to understand what “stone” is, we cannot establish the exact characteristics; and therefore, if we want to scientifically raise the question of restoration and conservation of this material, it is necessary to more precisely determine what kind of material we are going to restore.
A few examples will explain the matter.
So, everyone is more or less familiar with the malachite stone. If we compare malachite with marble, then their hardness and some other characteristics are more or less the same; even the color of marble sometimes resembles the color of malachite; but in chemical composition they are completely different. In one case we have copper carbonate, in the other calcium carbonate, and all further properties of these stones are different. The “stone” quartz or flint is so different in its properties from this “stone” or from the diamond stone that no comparison is possible at all.
Thus, from the point of view of the material itself, the concept of “stone” is extremely different, and therefore requires a more careful attitude to the very nature of this material. In practice, we must distinguish between two main types of “stone”: natural compounds of silicon (silicium) - silicates - and natural compounds of calcium and magnesium - limestone, marble, gypsum, dolomite, etc.
Silicon compounds with oxygen (SiO 2 silica) are the main part of a huge number of minerals, ranging from flint and quartz to basalt, Labradorite, granite, feldspar, etc.
Silica is extremely resistant to acids; only fluoric acid dissolves it, hydrochloric acid can transform it into a gelatinous state, but not dissolve it; but alloys of silica with potassium or sodium are soluble even in water (liquid glass).
On the contrary, the second group of “stones” (marble and others) are extremely sensitive to certain acids; these are compounds of calcium and magnesium with carbon dioxide (CaCO 3; MgCO 3); they slowly dissolve in water, but if the latter contains carbon dioxide, which often happens in soil waters, then the dissolution becomes much more vigorous. Calcium combined with a sulfuric acid radical (CaSO 4) - gypsum differs significantly from previous calcium compounds: therefore, a special group of “stones” is again outlined for practical work.
Stone technology for ordinary products is the simplest technology. The stone usually undergoes only simple mechanical processing. First there is a simple chipping of excess material, and then grinding, polishing, drilling, turning. The stone is usually not subjected to chemical treatment.
Thus, purely mechanical processing remains typical for stone; The study of this processing can again be carried out using the simplest methods - macroscopic and microscopic analyses.
An accurate mineralogical determination is made, of course, not by a historian or economist, but by natural scientists. For the elementary determination of a material, there are the simplest chemical reactions listed below.
The main factor of destruction for not very dense stone is a strong change in temperature combined with humidity. If the stone is porous, then moisture entering the pores freezes when the temperature drops, the volume of water increases, and the stone breaks. We observe this process on those stone objects that remain exposed to atmospheric conditions; for example, located on the square opposite the Winter Palace in Leningrad, a huge granite column is all riddled with cracks, formed precisely from the action of water, which, getting into the smallest pores of the stone, tore it apart when it froze. This is especially noticeable on the northern side of the column, which is obviously more susceptible to freezing processes.
The same thing happens with the magnificent columns of St. Isaac's Cathedral and the granite parapet on the embankments of the Neva, Fontanka, etc.
This phenomenon of stone destruction is extremely common in our climate; and where the climate is sharply continental, with sudden and sharp changes in heat and cold, “in addition to water, rapid temperature changes can also act destructively, since some rocks do not have a homogeneous composition, and the expansion coefficient of the constituent components is different.
In addition, air movement has a great destructive effect on stone. At the same time, the wind raises a large number of grains of sand, knocking off the smallest particles from the stone, often the entire stone is worn away by the action of the wind. This is the so-called weathering, which also includes the leaching effect of water. Even in areas with stable, calm atmospheric conditions, wind is an energetic destructive factor, and in countries with very strong winds, such as Central Asia, the weathering process is extremely rapid.
In conditions of a relatively mild climate, those stone products that belong to the second group, i.e., calcium compounds with CO3 (marble, dolomite), suffer the most, because they are much easier than silicates to be affected by freezing water, wind, and, unfortunately, some chemical factors. Such chemical factors include, first of all, sulfur dioxide, which enters in huge quantities into the air of industrial cities as a result of the combustion of coal in the furnaces of factories, factories, ships, etc. This sulfur dioxide, combining with atmospheric moisture, produces sulfuric acid and destroys carbon dioxide compounds already chemically. Therefore, in this case we observe the destruction of marble, the destruction of lime structures (plaster), etc.
Here calcium carbonate turns into gypsum, crystallizes and destroys the surface mechanically or is washed out with water.
Compounds of the third group, i.e. gypsum, selenite and others, are generally weak compounds, their hardness is low; they are used mainly for making small things.
With regard to compounds of this group, we observe a wide variety of mechanical and chemical damage. While in the ground, the stone is exposed to other influences. The fact is that soil water always contains some dissolved salts, most often sodium chloride salts. A salt solution, penetrating a stone, especially a porous one, saturates it like a sponge; If a stone of this kind, soaked in a salt solution, is placed in conditions of relative dryness, rapid evaporation of water begins, crystals of dissolved salt will be released from the solution, and the not very dense stone will rupture. Sometimes the process goes so far that the entire stone turns into powder, but even if the process does not go so far, the destruction from it is always very significant; The worst thing is that these destructions will be discovered precisely in the museum, that is, in a dry place. White deposits consisting of crystals, often quite large, appear on the surface of the stone product.
Salts dissolved in water can be very different: some of them dissolve very easily, others dissolve with great difficulty or are almost not dissolved. Of those salts that are easily dissolved, first of all we must mention table salt, i.e. sodium chloride, which is the main contaminant of almost all soil waters. If the air in the museum is dry, this sodium chloride, quickly released from the water, forms crystals, but if there is strong humidity in the museum, the sodium chloride will dissolve again, and again the table salt will be absorbed into the stone product. When drying, a new crystallization process will occur, etc.
These repeated processes of drying and dissolving in a museum setting are the main factor of destruction. Therefore, we usually try to remove sodium chloride first, firstly, because it is the most common representative of the soluble salts, and, secondly, because if we remove sodium chloride, other soluble salts will also be removed along with it: these are potassium chloride, magnesium chloride, calcium chloride, sodium and potassium carbonate, etc.
Insoluble or sparingly soluble salts are dissolved in soil water in very low large quantities, but if this or that thing has been in the ground for centuries and millennia, still, even with a small content of such sparingly soluble salt in the water, it is gradually deposited in large quantities, and objects are sometimes completely saturated with these salts, or a thick crust of salts grows on them , deposited on the surface; Most often we encounter deposits of calcium carbonate and calcium sulfate, i.e. chalk and gypsum with grains of sand, pieces of clay, etc.
The very first thing that needs to be done with an object extracted from the earth is to wash and remove soluble salts. We call this process leaching and it is carried out by soaking it in water for a more or less long time.
Consequently, a stone object in which we suspect the presence of one or another salt must first of all be thoroughly washed. To do this, put it in ordinary water. However, the water should not be too hard. By changing the water every day, we gradually wash out sodium chloride and other soluble salts from the stone product day by day. It is extremely necessary to control the content of chloride salts; it is produced with a weak solution of 1.5-2% silver nitrate AgNO 3. 1
Silver nitrate, when meeting with table salt or some other compound containing chlorine, gives a white precipitate of silver chloride.
Consequently, if there is even a small proportion of chlorine in the water, we will have white turbidity, and then a white precipitate, which will indicate that chlorine is still present and leaching has not been completed. Only the tiniest fractions of chlorine are tolerated, otherwise things will die.
For such hard rocks as granite, basalt, flint, such leaching does not have to be carried out, since water does not have the opportunity to penetrate into these rocks. On a hard stone there may be deposits and crusts on the surface, consisting of insoluble salts.
Sometimes putting an object in water to wash it away can be dangerous. In such cases, the item should be bandaged with an ordinary medical bandage or some kind of fixing substance permeable to water should be applied to it, for example, a gelatin film or a celluloid film dissolved in acetone (2%); with such a coating, leaching proceeds much more slowly, but can still be completed.
Another way to clean salts is to call the salts onto the surface of the item. This is done in this way: take filter paper, tear it into small pieces and put it in a flask with water, then shake it well; The result is pulp, which is applied to a particular object in a thin layer. What happens here is something completely different than when you put an object in water: in water there is a slow process of diffusion, but in this case, if you put paper pulp on an object and let this pulp dry, you will use a different property, namely the phenomenon of capillary rise solution: liquid together with salt from the depths will rise to the evaporation surface; When the paper dries, the salt crystallizes on its surface. By carefully removing the paper after it has dried, we remove some of the salt along with it. This operation is repeated several times. To control, you dip the removed paper into a glass of distilled water and test for chlorine with silver nitrate.
Any washing is done slowly, and haste here can ruin all the results of the work; It should be remembered that in restoration, slow, careful work is the key to success.
Al. Scott, in the laboratory of the British Museum, soaked some objects for 4-6 months or even more.
There may be even more sophisticated methods of processing, but what has been said is enough, especially if you are very careful and thorough in your work.
Of the salts that are sparingly soluble in water, the most common are calcium carbonate, magnesium or calcium sulfate. From hard silicate stone they are removed partly mechanically, and partly - namely, calcareous ones - with a weak (1.5-2.0%) solution of hydrochloric acid, after which thorough washing is necessary. From soft, loose stones (limestone, etc.), such removal must be done with great care so that the hydrochloric acid does not dissolve the object itself.
It is often necessary to secure crumbling or cracking stone. The first method of fixation is soaking with non-degradable fats. The most reliable remedy is paraffin. They take possibly refractory paraffin, melt it, heat it to 125° or dissolve it in xylene or toluene and immerse an object heated to 105-110° in it, i.e., so that there is no water left in it. The item should be kept in paraffin until the bubbles stop. If we then remove the object from the paraffin and let it dry thoroughly, we may end up with a greasy, greasy, unpleasant surface. This excess fat can be removed by gentle heating and removing the paraffin with a cotton swab or linen rag.
The second method is to use some kind of resin, in particular shellac resin. Shellac dissolves in strong alcohol. Usually it is enough to use a two percent solution. The object must be held in such a resin solution until the bubbles disappear. The result is a fairly strong fixation, but, unfortunately, such fixation in resin gives an unpleasant and unnecessary shine.
The third way is to use glue. Of all types of glue, gelatin is the most suitable for fastening.
Take gelatin in a 2-5% solution. The solution is prepared in this way. You should weigh out the required amount of gelatin and the corresponding amount of water, moisten the gelatin in this water so that it becomes completely soft, and then squeeze it well over a cup of water, and then, having brought this water to 60-80 °, little by little throw the soft gelatin. The object is immersed in such a solution, and in the same way as when fixing it with paraffin, it is held until the release of bubbles stops.
It is very important that the solution penetrates as deeply as possible: therefore, it is necessary that the object is well dried beforehand, it is better if it is warm; the solution must, of course, be hot.
When the bubbles stop appearing, remove the object and dry it. Usually one such procedure is enough to ensure that all particles of an object adhere; In rare cases, consolidation has to be repeated. Until the glue on the surface hardens, remove excess with a cloth.
But this cannot be limited. Gelatin, like any glue, is easily attacked by microorganisms and, therefore, we will turn the stone into an area for the development of colonies of microorganisms. Therefore, it is necessary to take some measures that would make gelatin inedible for microorganisms. To do this, expose the fixed object to formaldehyde. Formalin (40% ready-made commercial solution) is poured into a cup, saucer or onto a piece of paper; A teaspoon is enough to only slightly wet the paper: wrap it around the object and place it under a glass cover, place the latter on some kind of board or, better yet, glass and coat it with clay all around. The item is left under the hood until the next day. The cap must be removed in the air; the item should be allowed to air; As a result of this treatment, gelatin becomes insoluble in water and inedible for microorganisms.
Instead of expensive formaldehyde, you can use another tanning agent - white alum; they are placed in an amount of 0.5% by weight of gelatin in the adhesive solution just before use: the alum solution with alum is unsuitable for secondary work; alum is pre-dissolved in a small amount of hot water. I have a collection of objects fixed with gelatin about 20 years ago, and there are still no signs of destruction; in this case, the paints are not damaged at all, there is not the slightest trace of such impregnation, there is no shine, etc.
The fourth method of fixation is fixation with cellulose preparations. Cellulose is the fiber that is the skeleton of all plant tissue. It is obtained in the simplest way in the purest form from cotton fiber. Under ordinary conditions of museum work, we, of course, cannot obtain a cellulose solution ourselves, so we must turn to ready-made cellulose preparations. There are different types of finished cellulose preparations; the simplest and most affordable is acetate film. Film film is one of the cellulose preparations (cellulose acetate), characterized by good quality that it is little or almost not flammable. Some cellulose preparations are very flammable and even explosive, such as cellulose treated with nitric acid (nitrocellulose, zapon).
First of all, the film must be freed from the photographic layer, for which they take a 5% solution of ordinary soda, i.e. baking soda, and boil the film in it; after that, wash it in ordinary water to remove the lye; the result is a completely transparent, clean film; it dissolves easily in acetone. Make a 2 or 3 percent solution and saturate the object with this solution. Impregnation is done either by immersion or brush application.
In cases where it is impossible to immerse an object in one or another; fixative, this fixative is applied with a brush. Of course, any application with a brush is much more difficult than simple immersion, but fragile objects must be secured by applying a fixative with a brush. Shellac solution and cellulose can be applied with a brush and spray.
Often we have to glue stone objects.
The glue that is sold in stores under the name of stationery or even gum arabic or syndeticone has nothing in common with real gum arabic and syndeticone; it is liquid glass, which has a very harmful effect on many materials, and therefore the use of such glue in general in museums should not be allowed. under no circumstances is it possible. Cheap cellulose preparations are very common on sale. This includes all sorts of rapids, rolled oats, masterpieces, etc. All these glues without indicating their chemical composition are unacceptable in the museum; they are extremely unreliable, forming films that easily bounce off hard, especially smooth surfaces, which often leads to unexpected disintegration of glued things.
To glue small stone objects, you can use the same gelatin in a 25% solution in vinegar (7-8% acetic acid in water).
For larger objects, use putty made up of harpius (rosin) and wax in various proportions, depending on the hardness and strength of the fragments being glued together. The general rule is: the weaker the material of the object and the less weight of the object, the softer the putty can be. Recipes: for soft and medium materials, wax - two parts, harpius - one part. First, the wax is heated over low heat, then the crushed harpius is poured in little by little; for temporary addition of debris or very soft rocks, add rendered pork fat, depending on your preference, more or less.
For solid objects and mosaics: wax - one part, harpius - one part. In the first and second cases they work with heated putty and an object. When the putty cools, it is heated with an iron.
For very hard and heavier objects: putty No. 1, but without fat - 3 parts, clean, sifted alabaster - 1 part
For exceptional cases, where it is necessary to protect against shocks and shaking: wax - 4 parts, harpius - 2 parts, white Tsaregrad mastic - 1 part, shellac - 1 part, the components are introduced gradually into the molten wax. The putty is prepared for future use; consumed hot.
If you need to glue a large marble thing, you need to use cements, of which the best is magnesia, used for technical marble work.
There is another series of excellent putties, very strong, built on protein substances, such as: casein, egg white, etc. Casein is that solid part that, together with water and fat, forms an emulsion called milk. If milk is subjected to the oxidation process, fat will be released on top, and at the bottom you will get water and a white precipitate, the so-called curd; This cottage cheese must be thoroughly rinsed from fats and dried at a temperature of 30°. If the temperature is higher, it is easy to dry out the cottage cheese, but if it is lower, it will not dry out and will be prone to rotting. The result is a fairly coarse grain; large grains must be finely ground; if the washing was done thoroughly, and also the drying, you will get a good casein glue, which can be dissolved in ammonia (called ammonia in the hostel).
If this curd is ground with water and quicklime, the result is an extremely hard putty of exceptional strength. But it is clear that such a hard putty, excellent for very hard materials, is dangerous for loose things.
Instead of cottage cheese, you can take another protein substance - egg white mixed with quicklime. The result is a putty that is also very strong, but softer than casein with quicklime. If you take slaked lime, the hardening will be quite slow, but reliable; This putty is suitable for all kinds of shards.
For gluing, dry and slightly warm up those parts of the objects that need to be glued, quickly apply putty, connect the fragments and tie them tightly. This adhesion will be very strong if the moment of hardening of the protein is not missed, since lime immediately begins to coagulate the protein, which is why the putty must be ground in small portions and not prepared for future use. To prevent the putty from tearing very loose materials, some neutral filler is added to it, such as ground brick or marble.
Preservation for stone objects that have been well leached from salts consists of protecting them from excessive moisture if they have been glued together with gelatin. It must be remembered that sulfur dioxide and carbon dioxide are very dangerous for marble and limestone, which is why valuable monuments made of these materials in the open air in big cities can be seriously damaged. To protect against this, they can be treated with a thin layer of bleached wax; this work requires the participation of an experienced marble maker or restoration specialist.
It is also necessary to have an experienced marble maker present when soldering individual large parts of marble statues, since this requires introducing copper plates into the marble.
Marbles can be washed with a foam of neutral (baby) soap, then thoroughly washing off the slightest traces of soap, which is easily determined by touch. Instead of baby soap you can take a 2% solution of caustic soda (caustic soda), but you should not use baking soda because of the carbon dioxide, which dissolves the marble. Since any soap, even baby soap, hydrolytically splits off caustic soda in water, fears of a pure solution of caustic sodium are unfounded. The effect of any fats on marble is very undesirable, since they form on the marble a nasty-looking greasy film of lime soap, insoluble in water (but soluble in carbon dioxide). To avoid both caustic soda and soap, you can wash marble with a decoction of soap root (Saponaria officinals, etc.) or a solution of 2% borax, and finally - a weak solution of ammonia (5-10%).
__________1 More precisely, a decinormal solution of 1/10 N
N - 14,008 O 3 - 48,000,
which gives 169.888, simply 170 g per 1 liter of water, i.e. about 2%.
Contrary to the common misconception that there is nothing more reliable and durable natural stone, marble is very delicate and sensitive to external stimuli material. Marble is a soft, porous stone that is easily scratched and dirty and requires careful care. In this article we will try to answer how to clean marble.
Let's start the story with what you definitely shouldn't do.
How not to clean marble!
Remember, no matter how much craftsmen advise you, you cannot clean marble with vinegar, wine, orange juice, Coca-Cola, or any abrasive detergents (chalk chips, sand, etc.), any products containing acid (including for cleaning bathtubs), cleaning products for ceramic tiles. Even weak acids will destroy the structure of the stone, and powders and abrasive chips will leave scratches. Many companies offer marble cleaning; they come to you and clean it with abrasives so that later your marble will be unrecognizable. Run away from them as fast as you can. It is possible to restore marble after such cleaning, but you will spend much more money than buying a special mild detergent for washing marble.
How to clean marble
For daily care, just plain water and a soft cloth are enough. For light stains, stains can be removed using household cleaning products. detergent (soap solution, acid-free). To remove tough stains, you will need a special marble cleaner.
How to prevent marble from deteriorating and preventing stains from forming
If you have a marble floor next to front door, place a rug in front of her. Grains of sand and particles of dirt stuck to the shoes will constantly scratch the floor, and the marble will very quickly become dull and worn out.
If you have marble floors in your home, don't walk on it with shoes on. Whether you like to walk barefoot or not, this is the most reliable way to keep marble intact. The fact is that dust and dirt will certainly stick to your shoes, especially with hard soles, and even more so with heels, grains of sand will get into the sole, all this will systematically destroy and scratch the marble surface, violating its original appearance.
If you have marble countertops in your kitchen, try using cutting boards for cutting food. Place glass glasses only on coasters especially glasses of wine(wine has acid). Place hot dishes only on stands; do not remove them from the heat and place them on a stone countertop; a sharp temperature change may cause the stone to crack, or begin to disintegrate and crumble.
If you have a marble sink, bathtub, or shower, wipe down the surface with a rubber squeegee after each water procedure so that dull soapy traces are not deposited on the stone.
Try to wipe down your marble daily. The longer dirt remains on it, the sooner it will eat into the stone. Avoid using soaps and detergents made from refined petroleum products. They will make the stone dull and faded.
Can you coat marble with wax?, this will help preserve it. Use only clear wax and never apply it to white marble - the marble may turn yellow.
Many stains can be removed with a solution ammonia, but try not to use it too often, this will also harm the stone.
Daily marble care
All you need is water, a soft cloth and a piece of chamois. Wipe the marble with a cloth soaked in warm water, and polish to a shine with suede (or another dry cloth or towel). Once or twice a year, wash the marble with a warm detergent - a solution of mild dishwashing detergent will do. After this, rinse the marble again with warm water and polish it dry.
If you spill or drop something on the marble, try to clean it up immediately with a sponge or rag soaked in warm water. Do not leave the stain on overnight. If you just spilled wine, wipe it up as quickly as possible paper napkin, being careful not to rub, otherwise the stain may become embedded. Rinse several times with warm water and wipe with a dry cloth.
The most important thing in removing stains from marble is to understand the reason for their formation. Be a detective, understand what most often happens in the place where you found the stain, and what its origin may be.
Make a cleaning mass from some white (colored ones will leave marks) absorbent material (blotter, napkin, paper towel). Soak it thoroughly in the cleaning solution described below (depending on the type of stain). Spread the cleaning paste (do not use acids!) over the entire surface of the marble in a layer 6-7 mm thick. Leave it on the surface for a period of 1 to 48 hours, depending on the age and brightness of the stain. Cover the top with a damp cloth and plastic or film to prevent the mixture from drying out. Attach the film to the surface. (Theoretically, you don’t have to cover the stone with film, then you will have to wet the paste as it dries).
Removing stains of organic origin from marble (tobacco, tea, coffee, other drinks (excluding juices and wine), leaves, bark, urine and animal droppings).
Such spots leave pinkish marks. On the street they can gradually pass on their own, washed out by the rain and brightened by the sun. Indoors, they are best removed by bleaching. A mixture of a 20 percent solution of hydrogen peroxide and a few drops of ammonia is suitable. Soak your white mixture in this solution and let it sit for 24 hours. When finished, rinse the marble thoroughly with warm water and wipe dry.
Removing greasy oil stains from marble (oil, grease, cream, lotions, cosmetics, resin, etc.)
Such stains leave dark marks on the stone. As soon as possible Apply some absorbent powder to the stain - chalk chips or even starch. After some time (as it absorbs), remove the dirty powder and apply a new one. Leave for 24 hours. Remove the powder with a stiff brush dipped in a hot solution of household detergent. Wipe dry and polish. (Alternatively, you can wipe the powder with a rag soaked in ammonia). If, nevertheless, this alkaline option turns out to be not strong enough, you will have to use a solvent. Moisten the white mass (as described above) with acetone or amyl acetate (sold in pharmacies), open the windows, ensure good ventilation, and never use near fire or sparks. Try not to leave it for long.
Removing rust from the surface of marble.
Rust (brown stains from iron, greenish from bronze and copper) usually forms where marble comes into contact with metal lamps, bolts, nails, iron flower pots, etc. Use an industrial marble rust remover. Follow the instructions carefully and do not leave it on for long as it is a chemical and may break down the stone. Stubborn metal stains are incredibly difficult to remove and can remain on the stone forever.
Removing plant stains in showers and swimming pools (algae, fungi, mold, moss, lichen)
Wipe with a solution of ammonia or hydrogen peroxide. Do not even think about mixing them together; a chemical reaction will occur, resulting in the formation of a deadly poisonous gas!
Removing ink stains from marble (pens, ink, etc.)
Such stains can be removed with hydrogen peroxide, nail polish remover or acetone. Be careful, peroxide is suitable for light-colored stones; light stains may remain on dark ones! Acetone, on the contrary, is suitable for dark stone.
Rain stains and stubborn hard water deposits on marble.
They are removed with a dry, thin metal web (the kind used for cleaning pots, just choose the most delicate and thin one). Be careful - this is an abrasive that can remove the top layer of your surface, and then you will have to polish the surface
Juice and soda stains.
Such strong irritants destroy marble (break the shine), so if you spill liquid on marble, clean it up and wipe it off with a dry cloth immediately. Rinse the surface and wipe dry. If it is already damaged and the shine has disappeared, you will have to start polishing.
Cleaning dull marble.
Cleaning dull marble and giving it its former shine is a rather complex process that depends on where the marble surface is located, the type of marble, and what caused it to lose its shine.
You can use special marble cleaning products that are sold in specialized stores to add shine, but this is sometimes not enough due to the depth of damage to the marble surface. Then you will need the help of specialists who will polish the marble surface.
You should be careful about polishing liquids for marble, because... overuse may damage the surface.
Today we will continue to deal with marble and touch on its properties and defects that sometimes arise during operation. It can be classified as a medium-hard rock; it can be different, it depends on the density and composition, the hardness on the MOO scale can be 2-3 or 3-4. One of the properties of marble is porosity, like all natural materials. That's why natural stones classified as vapor-permeable materials. Oddly enough, it combines two properties that may seem contradictory to themselves: permeability to gases and steam and low water absorption, this is due to the size and geometry of the pores. The porosity of limestones is more extensive than that of marble, its fluctuations reach 27%, while for marble a maximum of 1%
A more porous type of marble can be called travertine, because... its origin occurs in sources of water; it contains a considerable amount of gas bubbles.
As already mentioned in the article “”, the properties of marble are inherent in the qualities necessary for finishing materials. Once again I will emphasize wear resistance, strength, density, easy processing, decorativeness and excellent polishing retention. But among the varieties there are also stones that have low wear resistance, so it is not recommended to use them for flooring.
Now let's talk about defects that may arise during the use of polished stone. It is not exposed to aggressive environments and moisture if the treatment is carried out in a factory environment. Over time, the structure still undergoes changes, because the internal connections between the crystals are destroyed, i.e. in professional language this sounds like surface weathering. The depth of the weakened layer sometimes reaches several cm. The most severe changes occur in places of mechanical damage - these can be impacts, scratches, if strong pressure is applied to the stone. Due to the disruption of the internal bonds of the crystals of the stone, the surface becomes spongy, pits and recesses begin to appear in it due to the loss of surface crystals. If areas are subject to strong mechanical stress, streaks and spots may form. white, they already consist of crystals that have been destroyed, but have not yet lost their connections with each other.
When the surface is weakened, it perfectly begins to absorb various contaminants, i.e. absorbs liquids, incl. and cleansing, and they pull particles of contaminants with them. It turns out that water and solutions transport dirt inside the material.
One cannot help but mention the defects that sometimes arise over time. They can be divided into 2 parts:
1) Surface damage, i.e. What can happen is the destruction of parts or parts, the occurrence of cracks, chips on the edges and corners, abrasion of the surface, and as mentioned above, surface weathering.
2) Change in texture, this is characterized by surface contamination, stains and changes in the color of the stone, and efflorescence.
Now, in more detail, as for the destruction of individual parts or details made of marble, this usually occurs during external cladding, and is associated with moisture getting into the cavities between the cladding and the wall; in winter, it freezes and defrosts. Plus, don’t forget about factors such as acid rain and shrinkage deformations, i.e. both collectively and individually there is a possibility of destruction of marble.
As a result of building settlement and impacts on marble, cracks and chips may appear at the corners and edges of marble parts.
Abrasion may occur on the floors and steps of stairs; its formation depends on the number of people in the premises (large), and the lack of normal care behind the surface, i.e. the abrasive load increases. Surface weathering manifests itself in the form of loss of polish, this is possible due to the lack of compatibility of the different species used in the cladding; powdery crusts can also form.
On floors, this may appear in the form of flaking particles and flakes of marble. Anti-icing reagents that are brought in from the street with visitors’ shoes can also cause surface weathering. This result can also be caused by using a considerable amount of water during cleaning and poor waterproofing.
Penetrating between the seams of the slabs, excess moisture gradually accumulates under them and begins to rise to the surface. When migrating through marble, it interacts with carbon dioxide in the air and combines with calcite, thereby converting it into soluble calcium bicarbonate. At the surface, moisture evaporates and calcium turns into insoluble salts. Gradually, the volume of salts begins to prevail over the volume of calcite and, as a consequence of this process, the destruction of the surface material. Efflorescence is formed during a similar process, but more on that in the next article. Now you know the properties of marble and the defects that sometimes arise during operation.
Products from natural decorative stone Over time, they become contaminated and become impregnated with new chemical formations that penetrate deeply into the crystalline structure.
Marble and limestone exterior cladding will need touching up after 5-10 years. Granite cladding does not require restoration for several decades. Internal cladding, with proper care, practically does not need restoration for an indefinitely long period. Marble cladding in underground conditions, if preventive measures are not taken, deteriorates prematurely and needs to be restored several months after installation. During restoration, the stone is washed, glued, cracks and crevices are sealed, and the original texture is restored.
The sugary destruction of marble is characteristic exclusively of external cladding. It is caused by uneven destruction of the surface layer exposed to weathering. At the same time, the rough surface of the stone resembles the structure of sugar.
Scaly destruction is characteristic only of marble-like limestones, characterized by heterogeneity of composition, and is largely manifested in humid conditions.
Cracks, spalls and other mechanical damage occur as a result of deformation of lined structures.
When processing manually with impact tools, pneumatic or electric bush hammers are used. This treatment is allowed on slabs with a thickness of more than 100 mm. All cladding elements, except abrasive ones, are treated around the perimeter with a narrow scarpel (20 mm wide), regardless of the overall texture of the slabs.
The seams between the cladding slabs are re-embroidered, and if there is a lead gasket, they are caulked.
Processing with abrasives is carried out manually or with electrified tools. This method is used only on flat and horizontal surfaces.
Vertical surfaces are sanded only with whetstones, since the grain abrasive is not held on a vertical plane. The facing seams are cleaned of mortar to a depth of 2-3 mm and washed thoroughly so as not to scratch the surface when polishing.
Polishing is carried out only with white powders, since it is difficult to remove traces of colored powders.
Efflorescence (efflorescence) is formed when low-quality cement, contaminated sand and additives - accelerators of hardening of cement mortars are used in quantities exceeding the established ones. The main reason for the formation of stains on the surface of the internal cladding is insufficient protection of the back side of the slabs from the moisture of the veneered surface, which causes staining of light-colored stones with iron oxides. Wooden wedges, caulking and other materials of organic origin must not be left behind the cladding, the decomposition products of which can also cause the formation of stains on the surface of the cladding.
To protect against dust, efflorescence and stains, the surface of the cladding is regularly washed, coated with protective compounds and periodically polished. Preventive compounds (for example, mastic based on wax and paraffin) are applied in a thin layer with a clean linen rag to the surface of the cladding, which has previously been thoroughly washed, and left for 3-4 minutes to evaporate the solvent. Then use an electric polisher to wipe the surface of the cladding to a mirror shine, and first tighten the felt circle of the polisher with a clean cloth.
The mirror shine of white marbles is restored using tin powder. For polishing stone various colors chromium and aluminum oxides are used.
In some rocks, especially marble, there are compounds of ferrous substances, which in the air, and especially under the influence of moisture, change their chemical composition, giving the overall tone of the surface of the product a yellowish or pinkish tint. This process of chemical action with simultaneous mechanical contamination of the pores of the stone is called patination, and the resulting yellowish or pinkish surface tone on marble is called patina. Patina gives the stone a “warm” uniform, sometimes subtle tint. Remove patina using chemicals or rough mechanical cleaning using sandpaper or a rasp is unacceptable, as this will damage the product.
Patinated marble products should only be carefully cleaned and washed from surface dust and dirt. Cleaning and washing the marble surface with sulfuric, hydrochloric acid or aqua regia patches is extremely harmful to the products, as the marble surface is destroyed, becoming dull and rough. The only acid allowed when restoring marble and limestone products is oxalic acid; it does not destroy the stone and is used to remove surface rust stains. Soda, like an alkali, also does not have a destructive effect on stone, so simple pure soda in weak solutions can be used for products stored indoors and without damage to the surface. Such a strong alkali as caustic soda cannot be used when washing stone, since it, getting into cracks and deep pores, can cause the surface layer of the stone to crumble due to crystallization of the remaining alkali in the pores and crevices of the product.
The most harmless and effective means for washing stone is simple neutral soap. Using soap, a brush, a sponge and hot water, stone products can be washed from any alluvial contamination.
If the surface layer of a stone product is partially destroyed, then before you start washing, you should secure the surfaces that are in danger of destruction. For this purpose, the following is used: marbleite - burnt magnesia with marble dust, diluted with magnesium chloride, followed by coating the surface with paraffin; chalk putty on gelatin followed by impregnation with formaldehyde; putty made from zinc white on natural drying oil. Only after sealing cracks and hair nets with one of the indicated compounds and drying them thoroughly can you begin to wash the product.
When washing marble garden architectural decorations, usually covered with lichens and moss, use neutral soap with the addition of pumice powder. The surface is rubbed with a brush or brush. Lichens that have settled especially firmly on marble are removed with a copper wire brush. The smooth and wide surfaces of marble are easily cleaned with natural pumice in a piece. Large vertical planes of marble are washed using sawdust, which, having absorbed soapy water, easily sticks to the surface of the marble, retaining soap and moisture on it and thereby speeding up the washing of dirt.
Oil paint from marble products is washed with preliminary softening with caustic soda, liquid soap or bleach. The surface of the paint is smeared with a saturated solution of such an alkali, then the softened paint is carefully scraped off with a sharp knife, while simultaneously washing the area with water. Before washing the product in this way, all cracks and damage on its surface must be well sealed so that they do not allow caustic soda to pass through.
In cases where old soot and dirt are not washed off from the surface of the product, steam cleaning is used. Products made from polished granite and similar igneous rocks are cleaned and washed using hard hair and soft wire brushes. Products made of hewn granite, limestone, sandstone, tuff and dolomite are cleaned by continuous hammering or surface treatment with a sandblasting machine.
Stains are found mainly on marble products and are removed using chemicals, the composition of which depends on the nature of the stain. The nature of the stain can be determined in some cases by its appearance. Thus, oil stains become yellow or dark brown over time. Copper or bronze stains are green in color, and sometimes bronze also forms brown stains.
Stains are usually removed using a poultice or patch with various chemical compositions. To remove an oil or grease stain, apply a paste of burnt magnesia mixed with gasoline or benzene. Oil stains are removed by applying a paste of 2 parts baking soda, 1 part fluff lime and 1 part sanded pumice. Iron rust is removed with a paste of 1 part sodium citrate dissolved in 6 parts water, as well as glycerin and chalk. When the paste dries, it is moistened again or removed and the stain is covered with a new layer of paste. Since this product acts slowly, for deep and severe stains you can use a paste consisting of 1 part sodium lye, 1 part slaked lime, 1 part liquid soap and 4 parts sawdust. The stain should be covered with this paste for 24 hours, after which it is washed off with water.
Copper oxide stains form where drips from bronze, copper or brass pieces adjacent to marble run off. To eliminate these stains, compositions used against rust stains are suitable. In addition, the following means are used: a) a paste of 1 part ammonium chloride and 4 parts powdered talc, mixed dry with the addition of ammonia water; b) a lotion made of white fabric soaked in a solution of potassium cyanide - 7.5 g per 1 liter of water.
Resinous stains resulting from contact with resinous wood (for example, when packing a product in a wooden container for transportation) are removed in the following way: first, the surface of the stone is rubbed with pumice powder, then a lotion made of cloth soaked in a solution of sodium phosphate and bleach is pressed tightly to this place. . Stain-removing compounds are used in the form of a paste, which is a mixture of chemicals with chalk, stone flour or other inert powder, or in the form of a patch consisting of several layers of fabric soaked in a chemical solution.
Stains from lubricating oils They are difficult to clean, so they should be removed immediately after detection. To do this, moisten a tampon made of white fabric, folded in three or four layers, in a mixture of acetone and amyl acetate (1:1), and apply it to the stain, pressing the tampon with a piece of glass or a marble slab. Glass and marble prevent rapid evaporation of the solution. The size of the tampon should exceed the size of the spot by 3-4 cm on each side.
Traces of oils are removed by applying a paste of lime, chalk or marble flour, sealed with pure gasoline, to the stain and leaving until completely dry.
Old oil stains are removed as follows. Asbestos fiber 8-10 mm thick, impregnated with amyl acetate, is applied to the stain, which is pressed with a marble slab.
A heated steel sheet is placed on top. Asbestos dries, it is moistened with amyl acetate. The steel sheet must be hot enough. The operation is repeated until the stains are completely removed.
Drying oil stains that form on the lining when jointing 1 seams with mastics made on drying oil are removed with great difficulty by repeatedly applying a cotton swab dipped in hydrogen peroxide. For the same purposes, use: a mixture of methyl alcohol with a 10% solution of trisodium phosphate in a ratio of 1:1 by weight. Asbestos cardboard 8-10 mm thick, impregnated with a solution, is placed on the stain to be removed, and a marble slab is placed on top, which is covered with a heated steel sheet. The operation is repeated until the stain is completely removed.
Filling alone is not enough to seal through gaps and large cracks. In such cases, before pouring, the crack or gap is fastened with brackets made of copper or brass, for which holes are drilled in the stone, in which the ends of the brackets, cut with a “ruff,” are strengthened. The walls of the gap are cleaned of dirt or traces of the previous restoration and moistened with water. After this, the gap on the front side of the product is covered with crumpled clay so that the pouring mass does not show through. From the pouring side, clay is applied so that a channel is formed with a hole at the top in the form of a funnel. In several places in the channel, holes are made to allow air to escape when pouring the mass. The ends of the brackets that fasten the stone along the crack are also poured using clay funnels (“leaflets”). The body of thicker brackets should fit into a groove cut into the stone. The prepared mass is poured into clay channels, and the holes (vents) are covered with clay as soon as the poured mass appears from them.
After filling the gap, the clay cannot be removed until it has completely cooled and the poured composition has hardened. The resulting mounds and nodules are cut off with a sharp tool, and places that are poorly filled with mass are sealed using a spatula or similar tool. If a dark stripe of fill stands out from the outside, take a little mass out of the gap and seal the groove with marble or another mass well matched to the color of the stone.
When sealing small cracks with compounds that are used hot (resins, sulfur), the cracks are first heated, then the compound is quickly rubbed into them, after which the stone is ironed with a heated iron several times along the sealed crack.
Broken or destroyed small parts can be restored by inserting from the same stone as the product being restored. To restore damaged parts of profiled steps, cornices and various shaped products, first sculpt the missing part from a soft material (clay, plasticine), and remove the plaster mold from it. Using a model cast in a mold, this part is made from stone, which is glued into the product, having previously been reinforced with staples and pyrons.
Inserts can be made from a mass prepared according to one of the above recipes and matched in color to the stone being restored. The model is cast in a plaster mold. Marble is imitated using a gypsum composition mixed with aluminum alum or glue water with the addition of rosin ( yellow), ultramarine blue (greenish color), cinnabar (dark red color), etc.
To reduce hygroscopicity, i.e. ability to absorb moisture from the air into its pores, parts of the product made from a gypsum composition are boiled in a saturated alum solution, soaked in linseed oil or boiled in paraffin.
