Painting in crude plaster is similar to the movement of a snail. The snail humidifies a surface on the way to facilitate to herself the movement. The artist's brush moving on damp plaster leaves the colourful dab drying longer than a trace of a snail on the soil which is drying up after a rain.
It is a little history
The painting by paints of walls which is carried out on crude plaster is called "fresh", and in Italian – fresco. The history of development of a fresco lasted not one century. Painting "freshly" still began ancient Romans with creation of dyes on lime.
The paintings found to Pompeii were made more likely on the dried moistened plaster (sekko) the structures containing a small amount of lime, covered from above with the substances containing tempera or wax. The fresco images decorating Romance temples of 11-12 centuries remained. In the 14th century (after long oblivion) dry plaster painting extended again.
Only in the 16th century at the time of the Renaissance there was full crude plasters painting of walls or buon fresco when paints on a limy basis apply on newly-laid plaster.
Michelangelo said that a fresco – dab which is not demanding changes physically is heavy to put courageous art as work of the artist writing frescos demands an exact courageous hand, ability at one stroke, the long time demands to work with high speed. Therefore not each artist was capable to work in the equipment of a fresco, and the skill was checked by fresco test.
The merit of creation of the equipment of frescos is deservedly given to the Italian masters. Italian artists were invited to other countries of the world to paint temples, cathedrals, palaces and other majestic constructions.
The equipment demanded imposing not less than 5 layers, special preparation of lime, solutions, paints, exact following to each point of technology, big expense of time. For 16-hour day the artist could issue at most 1.6 sq.m, and, every day from unpainted sites it was required to delete a layer of newly-laid plaster, and next day to impose it again. Many years studied the equipment.
With the advent of wall-paper, distribution of glue paints, change of tastes, aspiration to accelerate finishing process the demand of masters of a fresco quickly fell. Now true art of painting by water paints on crude plaster the few master restorers and a small part of the artists who are engaged in finishing to order own.
Example of the buon fresco equipment, Florentine cathedral, Italy
Among masters the modified technology allowing to reduce time expenses, to use partially modern materials, receptions is widespread. There are methods of imitation of a fresco.
The equipment of a wall-painting and painting by water paints on crude plaster
So, three stages of development of one of the technician of a wall-painting are tracked:
on a dry wall (tempora) the paints containing lime;
the water painting structures with lime addition after plaster dried, and then is repeatedly processed (secco or alsekko), or on a fresco underpainting by tamper;
limy paints on damp, newly-laid plaster (fresco, as fresco, buon fresco).
Each of the technician of wall painting has variations and is applied by modern artists.
Technology of painting on fresh structure includes a number of consecutive operations, the majority from which is carried out in the sequence:
preparation of a wall;
preparation of several solutions;
consecutive putting each solution;
preparation of paints;
creation of the sketch, drawing on the top plaster coat;
tight closing of a wall with a film;
painting on crude plaster (a direct and return order);
drying.
Preparation of a surface of a wall
This technology of wall painting is applicable not to all wall materials. For example, to gas-blocks or other weak materials the fresco is not applied for several reasons:
blocks are weak, do not maintain the weight of a plaster covering;
the ability of a gas concrete to select moisture at solution is high;
at violation of integrity of a wall precious work of the artist perishes.
Bricklaying and wall from sandstone
For the real fresco three bases are possible:
bricklaying;
sandstone blocks;
iron ore blocks (stone) are considered as the best wall material for fresco painting.
However modern masters perform fresco works and on concrete walls.
Isolated the basis (it is necessary for prevention of penetration of water from wall material) so earlier:
the site of a wall of ½ sq.m was warmed up a wide petrol or kerosene flame;
superficially heated place was quickly coated with the warmed asphalt mix with coal tar (1:3);
burned once with a lamp (heated mix was absorbed in a brick);
the "sharp" (not rounded) sand filled on a plate was transferred to the warm tar weight to which grains of sand were pasted;
processed the following site.
So the adhesiveness of a wall increased, the waterproofing was carried out. However such covering is necessary only if the wall is badly isolated, and water climbs it from soil.
Modern primers under fresco do not apply to preparation of walls.
According to modern requirements the height difference of a surface of a wall should not be no more than 1 cm. Therefore ledges cut down. The brick is processed metal brushes to receive a rough surface. The smooth brick is covered with notches. Delete dust.
One more ancient way of fixing of plaster on the basis was a driving in of galvanized hooks or nails with large heads (besides, isolation of metal from plaster is required). The plaster layer reaching 2-4 cm held these products. Nowadays use fiber glass grids.
Preparation of special plaster solution
Apply to fresco only the extinguished lime kept several years. In certain cases even buy the Austrian lime of ten years' clearing. For house application use material of three-year endurance. It is simpler to buy a ready pushyonka, but high-quality. It is involved in dough, maintaining not less than 2 weeks. Chalk impurity in lime is inadmissible.
Lime fuzz
Networks often recommend to use clean (washed out, without inclusion of clay or silt) river sand. In old times need of use of sand acute-angled, but not rounded was emphasized. To purity there were same requirements. "Sharp" sand allows to receive a covering stronger, than solution with rounded grains of sand. Sand of several fractions is required:
for underlying layers – is larger;
for overlying – more small;
the thinnest sand is necessary for the top layer.
Studying of the Tyrolean fresco coverings showed that dolomitic sand gives the highest durability to limy plaster.
Dolomitic sand
As filler brick powder well holds moisture in solution. It is better for them to replace sand of plaster weight for the top layer. The small pieces of a brick and powder brought in solution prolong time of life of plaster solution that is important for the painter.
Proportions:
dough for underlying layers – 1:4;
weight for the top layers – 1:2.5.
As an armonapolnitel added chopped hemp which well held moisture to old times. Such filler was used only for the lower layers. Read our detailed article about sand for plaster.
Features of plastering
In Renaissance plastered in two layers later:
lower – solution with coarse sand to which (solution) allowed to dry out;
top – solution with tonkozyorny sand / brick powder which was updated daily (that part it which did not manage to put the drawing).
Now the limy structure is applied in 2-3 layers, the first – on well humidified brick. The general thickness of plaster layer – 3 cm. The last layer (that which is painted) – not thicker than 4 mm. Intermediate layers, except penultimate, do not level to provide strong coupling.
Paints for painting
Are suitable for painting on crude plaster of paint, divorced on water. It can be traditional mineral dyes which do not become colourless at contact with limy plaster (resistant to alkalis), or modern glue, water or acrylic, even fluorescent. Such dyes as are deservedly esteemed by masters: yellow ochre, smalt, a blue azure, Umbro and others by means of which the multi-color picture is created.
As whitewash apply to frescos long since lime, extinguished not less than 3 years. It is filled in with water and maintained several weeks for elimination of causticity (not of all). Daily merge the infused liquid, replacing clean. Further shift in a glazed pot, place in the furnace, allow to begin to boil, cool. Having merged excess water, prepare balls and dry. Then lime can be pounded and used as water paint.
For paints of different shades use small capacities, for example, jars from under baby food are good.
The paints applied on a wall first look bright, saturated. But, drying, lose brightness, brighten. To have an idea what will be color on a fresco in old times used the umbra stone which is instantly absorbing water. Paint quickly dried and found the shade close to fresco. Now for receiving representation do trial coloring.
Also use paints which are called tamper or tempera. In them as binding substance serves the egg yolk. The tempera is applied for underpaintings and retouching.
Preparation and drawing sketch
Painting on crude plaster is impossible without drawing the sketch of the drawing on a wall. Apply a cellular way to transferring of the small drawing. For big fresco "cloths" invented a "cardboard" method. The sketch was drawn on cardboard in scale 1 to 1. Cardboard was put to a wall and saw how the fresco will look.
Did cardboard "binding" to a wall (through openings of the size of nut) priporashivat the plastered surface in several places for each site. Then cardboard was cut. Along lines of the drawing did openings for a priporashivaniye by coal dust or having punctured with a needle.
Having put a cardboard fragment on a wall (having combined with tags), moved lines of the sketch to the painted site. Now it is possible to use dense paper or a cliche.
Some artists painted cardboard with paints. It gave the chance to compare fresh painting to the sketch and in time to make changes. Cardboards of the famous artists are stored in the museums.
Preservation
After leveling of the top draft plaster coat all surface of a wall is hermetically closed a thin film so that under it there was no air. Air is accurately distilled from under a film, ironing it a sponge, or rolling the roller. Before a raspisyvaniye cut out a piece of a film, baring the site no more than 1 sq.m. Thereby in plaster the whole days necessary for full writing of a fresco keep necessary water.
Drawing of a picture
Technology of painting on crude plaster is various. Someone from masters begins with dark sites, gradually descending to light. Someone as in a watercolor, begins with drawing light dabs, gradually passing to dense dark. For the letter use the soft brushes which are not breaking the crude film which is formed on a surface of a plaster fresh covering.
The artist works with sites. Cuts off only that site of the preserving film which will be able to draw for change.
The consistence of the applied paint is also various – from liquid to similar to paste. Putting paint can be multilayered (depends on the artist's plan). One feature – the paint applied to remove it will not turn out. Water from paint is absorbed by a covering, the calcium which is contained in solution lime in exchange acts, protecting a film dabs.
Application in modern interiors of frescos
Applying technology of painting on crude plaster water paints, paint big rooms. Such painting beautifully looks at distance.
For house interiors the fresco is not worse at all, compliance of the size and a plot of the picture painted by water paints to room space, its sizes is only necessary. Also consider that the viewer will close be from painting that changes visual perception.
Unique equipment of frescos alsekko
The technology of painting mentioned above on a dry plaster layer demands use of paints on the basis of crude eggs, water and glue. Such image is resistant to water therefore it can be used for facades. Alsekko even more often decorates arbors, fences, retaining walls.
Striking example of the equipment alsekko — Leonardo da Vinci. "Last Supper" (1498)
It is simpler than the technician in application, allows beginners not to hurry, finding time and attention to details. Paints apply on already dried plaster substrate which before a raspisyvaniye is moistened. Paints are not absorbed in the hardened plaster layer in crude plaster therefore they can be washed away, making changes.
Wall painting on crude plaster — every time unique creation. Complexity of execution, need of knowledge of the equipment, special materials – all this affects the price. The similar performed work has to live long. This condition is promoted by the measures taken by masters at each fabrication stage.
Fresco from Pompeii 
(yet there are no estimates)
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