Plaster: composition and preparation

Plaster - this is a rough finish of walls and ceilings, as well as the facade of the building. After its application all other works begin. You can do it yourself or invite specialists to do this.

This stage of repair is important because plastering provides protection for surfaces. Especially you should not hesitate to finish the facade, as it is more vulnerable to external influences.

Despite the complexity of the work and a long drying time of the coating, plastering is a classic way of finishing the premises.

By means of plaster it is possible to embody the most different design decisions, to make surfaces with imitations of various invoices and materials.It is suitable for all types of surfaces - from brick to wood.

For interior plastering is divided into:

• structural - it is heterogeneous and gives a relief;
• textured - it is distinguished by the granularity of materials, gives a different texture, for example, under stone, wood or sand;
• decorative - gives the effect of painting, improves the appearance of the surface;
• stone - creates an original drawing;
• Latex artificial plaster - resistant to mechanical damage.

Exterior plaster is also capable of creating an attractive exterior of the building, but still its main function is to strengthen the walls and protect them from destruction. Most often it is applied in several layers.

The peculiarities of this type of finishing also include the increase in thermal insulation and noise insulation, imparting evenness and elimination of surface defects, water and fire resistance of the surface.

Most often for plastering use cement and plaster solutions. They are characterized by relatively low cost and fast drying.

To facilitate the work, you can use special plastering stations.as plastering is a rather complicated process that requires effort. This not only saves time, but also materials. Plastering station allows you to handle a large area at a time, which does not need further processing.

Due to the fact that the plaster is the basis for subsequent work, there are many requirements for it. The quality of the solution is determined by its strength, plasticity, good adhesion and optimum density.

It is necessary to pay attention to the composition and proportions of materials. The area of ​​application of plaster solutions and their function depends on it. Also the most important indicators are water resistance and fire resistance.

The strength and durability of the coating affects not only the composition of the solution, but also the quality of surface preparation. On concrete surfaces, the protrusions and holes are sealed, cleaned with special brushes. If necessary, put a metal grid, and before applying the plaster surface slightly moistened with water.

Brick walls also need to be cleaned and leveled. Before finishing metal surfaces, make sure that there is no rust. It is recommended to finish wooden surfaces with shingles or special shields.Shingles are thin wooden boards made in the form of a grid.

There are basic types of solutions and combined.

The main ones are:

• cement (the most durable);
• clay (reusable);
• calcareous (increase plasticity and adhesion);
• gypsum (fast drying).

Almost always, for the preparation of solutions, river sand is added to the base material, which has a positive effect on the strength of the finished composition and does not require purification.

Combined solutions consist of several basic materials and thereby improve the properties of the plaster.

Cement plaster is heavy, so it is a little difficult to work with it. Despite this drawback, the cement mix provides long life, durability and water resistance. Cement plaster consists of natural materials, therefore it is considered safe and environmentally friendly.

It is important to monitor the amount of sand added to the solution., as it can reduce the adhesion of the mixture.

Cement-lime plaster is renamed, if you need to get a more durable composition. However, the most important thing is not to overdo it, since a large amount of lime will have the opposite effect - the plaster can become covered with cracks. The ideal ratio of lime to cement mixture is 1: 3.

Cement-lime mortar is used for interior decoration of the building and for facade decoration.

Lime-gypsum plaster is used for finishing rooms with medium humidity (not suitable for a bathroom) with walls made of stone, wood and other materials.

It is important to take into account that the gypsum freezes very quickly. (approximately 10-15 minutes), so the solution is prepared in small portions. It is not necessary to dilute the solution in hardened gypsum - on the contrary, it will lead to loss of strength and adhesion. It is also desirable to divide the surface into small sections and alternately plaster them.

Clay plaster is the oldest material for decoration.Working with it can take a long time, because the clay must first be prepared. This type of plaster is used for rooms with very low humidity. Lime is often added to the clay mixture (for greater plasticity), cement (for increased strength), or gypsum (for quick drying).

The main distinguishing feature of clay plaster from other types is the possibility of dilution with water when fully cured. Thus, if too much solution was prepared and it froze, then water can be added to it again and used to finish the surfaces. In this case, the quality of work will not suffer.

Gypsum plaster, with such advantages as light weight, ease of application and high strength, has one drawback - the lack of water resistance. For a short hardening time, you can change the recipe of the gypsum mortar by adding tile or PVA glue.

Decorative (terrazitovaya) plaster is mainly used for the decoration of facades, sometimes for corridors. The possible composition of such a plaster is very extensive, but cement and color pigments are almost always used.For various imitations need special additives and the use of the necessary tools for finishing.

Terrazit plaster is distinguished by the level of grit, which depends on the filler fraction:

• fine-grained - fraction up to 2 mm;
• medium-grained - 2-4 mm;
• coarse - 4-6 mm.

Any plaster includes a filler, water and a binder.

The proportions of these elements in the composition of the solution also depend on the type of work:

• splash;
• primer coat;
• finishing layer.

For spraying use the least binder, and for the finishing layer more. This is due to the high strength of the finishing material.

Plaster can be carried out in all three layers, as well as only in one. Individual proportions are selected for each method. Compositions in which clay is present always contain a smaller amount of this material.

If you want to improve certain properties of plaster, then you can buy special additives. For example, plasticizers increase the plasticity of the mixture and provide a smooth coating, prevent delamination. They can also reduce the amount of water required.

In the cold season, additives with antifreeze properties will help to carry out finishing work by not allowing the solution to freeze. The quartz sand increases resistance to acids, mica protects from an ultraviolet. Metal shavings are rarely used due to their corrosive properties, but they increase the strength of the coating.

There is also a wide range of decorative additives:

• marble chips are used to create a Venetian style;
• flocks (colored acrylic pieces) give a suede effect;
• wax and resin additives are used to imitate stone, silk.

The main rule when using additives is their amount, which in solution should not exceed 10% of the main volume. Some additives can be introduced into the solution with a syringe.

The difference between the plaster and the usual putty is that the putty is a finishing finish and hides the defects that were made during the plastering.

To prepare the plaster solution, you must use the following tools:

• capacity for materials;
• concrete mixer (can be replaced with a mixer or a shovel);
• binder, aggregate and water;
• dispenser.

To prepare cement plaster, you first need to sift the sand and clean it from debris and lumps. Then carefully mix the cement and sand in a dry form. To do this, use a concrete mixer or mixer. As soon as the elements become homogeneous, you can gradually add water, gently continuing to stir. The finished composition should acquire the condition of thick cream.

In terms of the fat content of the mixture is distinguished by:

• fatty (has a strong stickiness);
• normal;
• lean (no stickiness).

High-quality mixture should be different uniformity of composition and normal fat.

To prepare the clay solution, it is necessary to soak the alumina in water for several hours, and then knead so that there are no lumps. After that add sawdust to clay. Alumina in the end should be quite thick. To achieve this result, you need to constantly mix the mixture and add a little water.

To completely get rid of lumps and debris, you can wipe the solution with a sieve.After these actions, sifted sand is added. But such a mixture will not have sufficient strength, therefore, cement, lime or gypsum is additionally added to it.

To prepare a lime based plaster, it is necessary to use only the hydrated substance. First, this material is mixed with water, and then sand is gradually added.

It is possible to determine the drying of the plaster by changing the color from grayish to white. The finished mixture in the tank can be stored for about three days, but it is not recommended to delay its application, because over time the solution begins to lose plasticity.

If lime is not extinguished, then it is necessary to make a slaking. To do this, dry lime is diluted with cold water. It is important to use a large volume capacity, since quenching is a violent reaction. Safety glasses and clothing may be required. Lime should last for about two weeks

Cement-lime plaster can be made by hand in two ways:

• Dry mix cement and sand, then you can dilute them with lime milk, cleaned with a sieve. All elements are thoroughly mixed.
• First, lime, sand and water are mixed, and then cement is added. Also, the resulting mass is mixed.

Decorative plaster can be made of any binding materials, but with the obligatory addition of decorative additives and color pigment.

Recipes for the preparation of solutions are not very different, but the characteristics of the materials used are taken into account.

To independently prepare the solution, you must perform the following steps:

• all dry plaster materials must first be sifted and completely cleaned;
• to be sure of the homogeneity of the resulting composition, it is desirable to filter it;
• the proportions of materials in the composition are governed by the types of work (spray, primer or finish).

Nowadays, ready-made dry mixes can be purchased that need only be diluted with water. They are good because they have a professional and specialized composition, contain various additives to enhance strength and ductility.

The quality of the final plaster depends on the correct preparation of the composition and compliance with the proportions of materials. Errors may result in cracks on the surface, flaking, swelling.

Poor mixing of the solution leads to cracks. due to the high concentration in one area of ​​the binder or aggregate. More cracks appear from exposure to too low or high temperatures, drafts. Therefore, after applying the plaster is best to close all windows and doors.

New layer can be applied only after complete drying of the previous one.

There is a misconception that if you add more cement, then the strength of the solution will increase. But this is not true. Of course, the solution will become denser, but when dry, cracks quickly form on the surface.

Before applying the plaster, make sure that the surface is completely dry. Otherwise, the coating will not be well fixed and will quickly peel off. But the dry surface will not hold the coating. Also it is not recommended to make too thin or thick layers.

For better fixing of the plaster mix it is worth making sure that the surface is sufficiently rough.If, however, layers of different thickness are applied, then after drying it will be noticeable due to the non-uniform color of the surface due to the different length of drying time.

The strength is influenced by the amount of binder and the absence of impurities in the materials. It is impossible to use plaster plaster for concrete surfaces, it can lead to destruction of the surface. Also, it is not recommended to apply lime mixture to gypsum.

Although it is not recommended to influence the self-drying time of the plaster, but if you ensure good ventilation in the room, the probability of occurrence of defects is reduced.

Before plastering a brick, it is better to moisten the surface.as this material possesses good absorbency of moisture. Before finishing, it is necessary to completely clean the surface from any contamination in order for the solution to show better adhesion. Do not forget about the preparation for plastering the facade - if there are reinforced concrete beams, they are closed with clay baked in the furnace.

It is undesirable to use plaster plaster for exterior decoration, as it is deformed under the influence of rain or snow.To obtain a perfectly smooth coating on the surface, you can install beacons. To do this, you first need to check the verticality of the wall, and then drive in the dowels in the right places and stretch the line along them. To avoid a break, it is necessary to tighten the line between the outer beacons.

To fix uneven corners, put an extra layer of plaster. If the irregularity is too large, then first completely knock off the layer of plaster and reapply it.

It is best to carry out plastering in spring or autumn, when there is no hot sun or severe frosts. From the sun, you can cover the surface with a special protective canopy.

A thick layer of mortar may crack, but if it is necessary, it is necessary to stretch the metal reinforcing mesh before applying it. It is advisable to carry out all installation work before plastering, so as not to damage the coating or pipes (wires). Elements of communications are placed in special grooves in the wall and covered with plaster. Heating pipes should not be left close to the plaster, as they expand when heated and the coating collapses, and rust stains may occur due to the ability of gypsum to absorb moisture.

The surfaces must be completely free of dust, otherwise the plaster will not adhere properly to them.

How to knead the solution on the plaster, see below in the video.