Plastering walls for painting: quality requirements, choice of material and technology

Plastering correctly is essential to getting a smooth, faultless finish on walls, especially if painting is your plan. It is vital to get the plastering right from the start because it directly affects the final paint job’s appearance. A properly prepped wall guarantees that the paint goes on smoothly and appears flawless.

Plastering requires careful consideration of both the materials to use and the application method. There are various kinds of plaster that are appropriate for different situations and demands. Knowing which paint-ready materials are appropriate for your walls will help you achieve a smooth, long-lasting surface.

In addition to choosing the appropriate plaster, application technique is critical to the final result. There are several methods, each requiring a different set of steps and equipment. By following the right process, you can be sure that the plaster sets correctly, giving your paint a solid and even base.

Requirements for the quality of finishing for painting

Sanitary norms and regulations, or SNiPs, specify the requirements for surface finishing. In accordance with SNiP 3.04.01-87, "Insulating and finishing coatings," the following criteria must be met for walls to be suitable for painting:

• the walls that are planned to be plastered must be cleaned of dirt, grease stains, construction dust;
• The surfaces when painting must be smoothed, not have roughnesses;
• all cracks are opened, filled to a depth of at least 0.2 cm, and sanded;
• uneven areas are primed and smoothed out;
• traces of the trowel, drips and peeling are unacceptable, removed;
• uneven areas are acceptable, but in minimal quantities: no more than one minor defect up to 1 mm per 2 square meters;
• after finishing, the surface is primed, and painting is carried out only after complete evaporation of moisture.

The type of plaster will determine the requirements for completion of the work. The allowable thickness for a single layer of material is up to 2 cm (any solution, excluding gypsum) and up to 1.5 cm (gypsum mortar).

In the case of multilayer plasters devoid of polymer additions:

• splash on stone, concrete, brick – no more than 0.5 cm;
• splash on wood – up to 9 mm;
• cement primer — up to 0.5 cm,
• lime and (or) gypsum primer — up to 7 mm,
• final plaster layer — up to 2 mm,
• final finishing layer — 7 mm.

Plaster can be made to be high-quality, improved, and simple.

Gaps, bumps, and cracks in walls that have been plastered over are not acceptable.

Making the right material and technique choices will guarantee a smooth, even surface when plastering walls in preparation for painting. This entails picking premium plaster that is appropriate for the type of wall you have and applying it carefully to prevent flaws. In order to achieve a finish that maximizes paint adhesion and aesthetic appeal, meticulous preparation and attention to detail are essential.

Which plaster to choose?

Plaster is used with a mineral binder, such as gypsum, cement, lime-cement, or clay, to level walls before painting. The first two are used the most frequently.

Popular coatings’ characteristics

Gypsum mortar does not shrink, is more elastic, and is simpler to apply. The material also guarantees fire safety and is friendly to the environment. However, it has a quality that can be advantageous or disadvantageous: it sets quickly. On the one hand, this allows the subsequent layers to be applied rather quickly. However, in order to lay the prepared amount in thirty minutes, you must mix a small portion at a time.

For at least two hours, cement plaster does not lose its elasticity, so you can mix a big batch at once. It works on any kind of surface. Additionally, the mixture is less expensive. However, it can shrink, and the drying process takes a while.

Crucial elements that influence the selection of plaster for painting:

1. Gypsum plaster does not contain sand, so it is much smoother. It is used for interior finishing.
2. It is impossible to create walls without roughness using cement-sand mortar. But it is suitable for damp rooms and outdoor work.

Both varieties of plastered walls have excellent painting. The surface will be smooth in the first scenario and moisture-resistant in the second.

Leveling technology

There are minor phases to the entire finishing technology used before painting:

• preparation of walls, priming work;
• leveling with plaster solution;
• priming of leveled walls again;
• puttying;
• grinding-grinding;
• priming the surface before applying paint;
• painting.

Surface preparation

The surface is cleaned before any work is done. Plaster is intolerant to grease, dust, and fragments of old finishing from construction projects. As a result, thorough cleaning is necessary. Next, a primer with deep penetration is used. It has antiseptics in it. This kind of treatment will assist in preventing future mold and mildew growth. Plaster sits nicely on the primer, which is an advantage.

Construction beacons are placed on the surfaces to regulate the alignment process after a reinforcing mesh is fixed if needed. Only plasterboard sheets that are either affixed to the wall directly or to the frame can be processed in their absence.

Plastering on beacons

Beacon profiles are used in plastering to achieve the perfect surface and, consequently, a flawless painted wall. Plaster is uniformly distributed between these vertical guides. A rule that moves in a single plane made by beacons levels the solution.

Sagging the walls is a necessary step before installing beacons. It may be horizontal or vertical.

Horizontal. A dowel is inserted between 15 and 20 cm from the corner and ceiling. It should be 12–13 mm longer than the biggest bulge when it protrudes from the surface. It has a thread attached to it with a plumb line. Next, a second dowel is installed. After tugging, the thread is fixed. Once the level is perfectly aligned, the screw is then tightened. In the other corner, the same algorithm is used.

Horizontal. requires tensioning the threads diagonally in order to obtain the plane’s middle at their intersection. There, the screw will be inserted. From there, horizontal markings are made to the corners using a level. They also have self-tapping screws installed in them, and the thread is pulled. Using a level, the geometry is examined once more. If the thread comes into contact with the surface, it needs to be adjusted or fixed by undoing the screws.

The accuracy with which the process is carried out determines how smooth the walls will end up being. Following that, gypsum mortar is used to fix the screws and apply a beacon.

Crucial! The process is only carried out with level control. After the beacons are firmly in place and the gypsum support points have solidified, plastering of the primed walls will start.

The beacons are covered with plaster in stages. Using a rule, the first layer is sprayed and leveled. The next, thinner layer is applied after it has dried. It removes flaws from the initial coating. The third stratum is required.

After that, grouting is done. All of the grooves and areas where the putty is layered are rubbed with a fine-mesh grinding block. The less work required for grouting, the better the puttying is done.

The walls are puttied once they have dried and leveled. This is the last step in the finishing process for wallpaper or paint.

Read our article to find out more about the differences between putty and plaster. In summary, putty is finely grained and useful for cosmetically finishing irregularities up to 15 mm, while plaster mixture has large grains and is meant to level rough defects up to 5–6 cm. Putty-treated surfaces have a smoother texture.

Puttying walls

1. Water is added to the dry mixture. The consistency should resemble thick sour cream and stick to the spatula without dripping from it.
2. First, a starting layer is applied to a large spatula with a smaller one. It is applied to the wall at an angle of up to 30 degrees. The main condition is uniform distribution. Each subsequent layer overlaps the previous one by about 5 cm.
3. Corners require careful processing, especially internal ones. It is better to use a corner spatula.
4. When the starting layer dries, the finish is applied using the same technology. The layer should not be thicker than 2 mm. Each subsequent layer is applied after the previous ones have dried, after about 4 hours. But the last layer should dry for at least half a day or longer.
5. Paper with a grain from P120 to P150 is required for painting.

Puttying is not necessary when the surface’s perfect smoothness is not a top priority. Glossing the plaster layer and painting the walls without puttying can take the place of this step.

When plastering walls for painting, careful consideration must be given to the selection of materials and application methods in order to achieve a smooth and long-lasting finish. Plastering done well not only makes your walls look better, but it also prolongs their life by giving paint a stable, even surface to stick to.

When choosing materials, take your project’s particular requirements into account. Because of their fine texture and ease of application, gypsum-based plasters are perfect for interior walls, while cement-based plasters provide more durability in high-moisture areas. To prevent future problems, always give priority to materials that guarantee compatibility with the paint type you have chosen.

Plastering requires careful surface preparation, accurate application, and enough drying time to be successful. You can be sure that your painted walls will have a flawless, long-lasting professional finish if you follow the recommended practices for each step.

Video on the topic

PUTTYING WALLS FOR PAINTING THE FIRST TIME

Finish plastering of walls: how to prepare walls for finishing coatings according to the Q1-Q4 quality system