- Basic concepts about marble plaster
- What surfaces can be finished with Venetian
- How to properly prepare the surface
- How to choose and prepare material
- What you need to work
- Application techniques
Very often, disappointment with the choice of Venetian plaster is associated with a deterioration in appearance due to loss of richness of color or the appearance of cracks. will tell you how to properly prepare the base for Venetian plaster, how to choose materials and colors, teach the application technique.
Basic concepts about marble plaster
Venetian plaster has been known for a very long time. Waste from quarries, where precious stones were processed, was crushed and mixed with slaked lime. When mixed with water, a very plastic mass was obtained, which could be applied in a thin layer and leveled to a state of almost perfectly smooth plane. In modern finishing materials, the lime binder has given way to a polymer one, but the essence has not changed from this. As before, the walls of the most presentable rooms are decorated with Venetian..
In everyday life, marbled plaster is appreciated for its aesthetic properties and relative cheapness. The coating naturally glows due to the translucency due to the properties of the marble powder. Modern coloring pigments allow you to give a bright, rich shade, and a specific application technique makes each square meter of finish unique and allows you to achieve very interesting artistic effects.
However, the Venetian is more expensive in comparison with wallpaper or textured plaster, especially considering the cost of the services of a painter with artistic skills and a designer who can choose the right color and pattern. The material itself is very durable, but if the technology for preparing the base is not followed, cracks and delamination may appear after just a few years of operation..
What surfaces can be finished with Venetian
Plastic and malleable plaster based on acrylic binder loses its elasticity after curing and does not resist stretching well. Therefore, the main rule when performing this kind of finishing is to ensure the stability of the base and by all means to prevent the development of cracks..
False walls made of plasterboard are best suited for these purposes, which themselves are quite strong and at the same time separated from the vibrations of the supporting structures, because the frame is fastened to the base on the basis of flexible ties. Monolithic partitions and walls of panel houses are also well suited. Although they are constantly moving relative to each other, the plane itself remains quite stable, you just need to visually hide the abutment lines.
Stone masonry is least suitable for Venetian decoration. It constantly perceives vibrations of the foundation and deforms, which leads to multiple occurrence of cracks. Nevertheless, with some effort, it is possible to apply a Venetian, although such an idea needs to be planned even before the start of the rough finish..
How to properly prepare the surface
The plaster layer itself is extremely small, in rare cases it reaches 1–1.2 mm. Therefore, the composition is not used for leveling, it is impractical, first of all, because of the high cost. A leveling layer must be made under the finishing plaster; gypsum putty is best suited for this. Alignment tolerance is only 1 mm / m in any direction, because on a glossy surface any curvature of the plane will be clearly visible.
Sometimes the maximum permissible thickness of the finishing filler is not enough to compensate for unevenness in the base layer. In this case, it is necessary to carry out preliminary alignment to a tolerance of 3 mm / m and up to 6-8 mm in the general plane. A qualified plasterer will be able to do this with a cement-based mortar using beacons. If the base plaster does not meet the leveling requirements, you will have to apply an intermediate layer of starting gypsum plaster with a coarse-grained binder..
As a result of preparation for Venetian style, the rough wall covering can be a rather complex cake. There is only one way to avoid the formation of voids between layers – by thorough intermediate priming. For example, if the ability of the substrate to absorb moisture is too high, which applies to lime and cement plaster, it is necessary to use deep penetration primers. For concrete and brickwork, formulations that improve adhesion due to the content of fine stone dust are suitable.
Reinforcement of walls will help to anticipate the opening of cracks, and it must be performed for each preparatory layer. Cement and cement-sand plasters should be reinforced with galvanized mesh. It will help maintain a sufficiently thick plaster layer and prevent the opening of cracks that appear during shrinkage. Pre-leveling with starting gypsum plaster should be carried out on a fiberglass mesh. With its help, it will be possible to exclude the appearance of a visible web of cracks formed by fluctuations in humidity and temperature. Finally, immediately before the final leveling with gypsum putty, it is recommended to glue on the wall fiberglass with a density of 30–35 g / m2. This will eliminate the appearance of microcracks on the finishing coating, into which dust and dirt are crammed..
After finishing puttying and sanding the surface, the entire wall must be impregnated with a primer for highly absorbent surfaces. This is necessary to hold all layers together and reduce hygroscopicity, so that it is convenient to work with the Venetian.
How to choose and prepare material
All Venetian plasters are initially white and do not provide any valuable visual effect. A pattern imitating a cut of marble is formed by overlapping many thin translucent layers that dry quickly upon application. Due to this, a set of scales is formed that imitate the structure of a natural stone..
To achieve this effect, the distribution of the dye in the plaster mass should be as uniform as possible. With self-tinting, an acceptable result can be obtained only under the condition of careful dosing of the dye on the scales and long-term manual mixing with two pouring of the composition into a clean container.
It is much more correct to turn to the services of computer tinting, choosing the desired shades according to the fan-palette. For the simplest artistic composition, only two colors are enough, differing by 2-3 tones. You should not make the Venetian too contrasting, this is acceptable only in fairly spacious rooms, where large, prominent veins are formed during application.
If you want to get confused with the artistic component of the coating, you can, in addition to the main color, choose another 1-2, differing from each other by one tone, and an additional contrasting one. The amount of materials should be determined in advance, taking into account the planned application technique. But you need to remember that tinted compositions can also be mixed with each other by rubbing the plaster with a spatula along the palette.
What you need to work
To begin with – completely clear the room of building materials and tools, leaving only 1-2 platforms and a ladder. It is necessary to carry out a general cleaning and get rid of dust as much as possible. It is necessary to organize high-quality lighting, the main source of which is located on the side of daylight incidence. The room must maintain a humidity of at least 60% and a temperature in the range of 20-25 ° С during the entire operation..
The plaster is applied with a rectangular trowel and a metal trowel. An ordinary Chinese instrument is also suitable, but it is better to give preference to products with an ergonomic handle, because there is a lot of work and calluses can become a serious problem. The width of the blades should be selected in accordance with the planned detailing of the drawing. Remember that each layer of Venetian should ideally be applied continuously over the entire surface to be treated. In this regard, it makes no sense to fill a wall with an area of 50 m2 fine strokes using a spatula with a 40 mm blade.
You also need a bucket of clean warm water and a large amount of rags. Residues are constantly drying to the blade of the spatula, so the tool must be periodically cleaned to avoid the ingress of dried fragments onto the applied plane.
First, with the base color, the entire plane of the wall is covered with cross strokes. At this stage, beginners are given the opportunity to get acquainted with the material and its properties. The plaster must be stretched very thinly, holding the trowel at an angle of 45 ° to 70 °. When working with a trowel, application is done by pressing the plane of the tool and quickly stretching the plaster spot in an arc in different directions.
If somewhere the strokes turn out to be torn, there is nothing to worry about, the gaps just need to be covered with another thin layer. After applying the base, the wall not only receives the main color, but also a smooth glossy surface is formed, over which the composition can be stretched with a very thin layer.
The second and subsequent layers are applied using artistic techniques:
- Classic marble cut. Performed in the same tone as the base. The thickness of the strokes can reach 0.3–0.5 mm, however, after decorating a small area, the surface must be smoothed by pressing the trowel close. Low transparency of layers creates calm, measured visual noise.
- Ripples. The base should be two tones darker than the top layers. Application is carried out in a single selected direction, usually at an angle of 20–35 ° to the floor. A wide stroke is directed along a common line, at the end of the movement of the spatula, it is slightly turned to the side, starting a stroke on the already covered section of the wall. This technique is applied 3-4 thin layers.
- Stone with contrasting veins. A curved mesh with a sufficiently large step and unequal mesh size is applied to the light base with cross strokes. After that, the wall is covered with short medium-tone strokes. They are applied more often in the area of veins and less often in the area of light areas..
- Azure. It is carried out with paint in cold shades on a white or light blue base. A trowel with a few drops of the composition is firmly pressed against the wall. The boundaries of the spots obtained are blurred with small strokes, leaving thin light veins.
- Crack effect. It is created after applying a coating with a sufficiently large number of irregularities up to 0.2–0.3 mm to the base. The dried surface is rubbed with a metal spatula, metallizing the tops of the relief. You can smooth out the contrast with light plaster, applying 1-2 layers of wide, but very thin strokes.
- Glacier in the sun. Gold pigment is added to the base material, the main color is chosen in a warm light tone. The decor is applied in a cold pastel tone: rather large spots are formed with rather sharp boundaries, strokes follow from the edge to the center of the spots. After the border of the spots, you need to lightly shade with small strokes or metallize. The remaining golden streaks imitate the play of light in ice cracks.
- Camouflage. The base is applied with small strokes, the material is a mixture of saturated and white, which is prepared by rubbing two compositions in equal proportions over a trowel. After that, a semi-contrast shade is selected (for example, coffee with milk is suitable for a muted burgundy base), a small stencil is left by pressing the trowel. The stains left must be carefully rubbed from the center to the edges with a slight overlap. The composition can be covered with one layer of thin strokes of putty with silver pigment.