Before painting the walls, you must carefully prepare their surfaces. On how this type of work is performed, the final result depends. Stain painting reveals small and large defects on the wall surface. Hence, the preparation must be carried out with the utmost care.
The exception is structural coatings. They sufficiently smooth out all irregularities. Before starting work, make sure that all the cables are installed so that you do not have to shred the already prepared walls.
New walls with fresh plaster. In this case, everything is simple. It is necessary zashpatlevat surface of walls and carefully cleaned them with sandpaper. Before painting, the walls are washed, dried and covered with a special primer.
On the walls is an old finish. First of all, you need to remove the old finish. Next, the walls should be leveled, dried and primed.
Cleaning walls before painting
First you need to determine which type of paint covers the wall. It is not difficult. Let’s take the sandpaper and use it for the wall. Paints made on a water basis will remain on the abrasive. Alkyd and oil paints are easily removed using sandpaper by simple shaking. Prepare a spatula, coarse-grained sandpaper and a metal brush. Carefully remove all old paint from the wall. Next, cover the surface with a thin layer and treat it with a primer.
For paints with a water base we select primers also on a water basis. Universal primers based on acrylic binders will work well. For enamels take an alkyd primer. To easily remove oil paint from the wall, the surface is washed with a 5% solution of soda.
Water-dispersion paints are removed with wallpaper paste and old newspapers. Glue the walls with glue and paste newspapers. Next, wait until the glue is completely dry. And then you will get the result – the paint will easily be taken off with the newspapers.
If the paint was made on an adhesive basis, then it can be removed with a 2% solution of hydrochloric acid. The surface of the wall is covered with bubbles and well washed away. After removing the paint, the walls are washed, dried and sanded.
Washing walls before painting
After removing old coatings, all uneven places on the walls should be cleaned with pumice stone or fine sandpaper. If there are stains of rust, they should be washed with water and primed with copper sulfate (10% solution), so that they do not then come through a new finish.
Oily stains are well cleaned with a 5% solution of soda ash. Mold must be washed off with warm water and household soap (removes the smell) and treated with fungicides the surface within a half-meter radius from the spot.
After that, you need to assess the condition of the entire surface of the walls: if it is even, then easy to clean first large, then fine sandpaper. If there are small pieces of separated plaster, cracks, chips, then they must be primed and leveled after drying.
In the case where the wall is uneven or the layer of putty is already old, it is best to clean it completely with a spatula. After this, the walls need to be treated with a soda, ammonia or soap solution, which will need to be washed off with plain water.
Make it perfect
If you had to completely clean the walls after the old coating to the base, they need to be plastered again. On a clean surface, a layer of primer waterproof material is applied to increase the adhesion of the plaster to the wall. Then, throughout the area of the room, beacons are placed along the most prominent places and a layer of plaster is applied until the wall is completely leveled.
Most often in the premises use:
- Lime solution: a weakly resistant mixture with high environmental characteristics.
- Gypsum plaster for rooms with low humidity.
- Cement-sand mixture: waterproof, strong, suitable for exterior and interior finishing works.
If the walls are even, you can do without plaster. It will take from one to three layers of putty to make the surface perfectly smooth, without defects: chips, cracks, areas of different thicknesses. Each layer thickness from 0.5 mm to 1.5 mm is superimposed after drying and grinding of the previous one. In some cases, a special net is used, a so-called spider web made of a thin reinforced glass fiber, and only then putty is applied.
Each layer applied must necessarily dry out, this is an important condition. Without its implementation, the stains will appear through the paint and the surface will not turn out to be perfectly smooth. Drafts and cold can slow down the drying time and spoil the prepared surface, so the windows and doors in the room after work must be closed. The dried wall is sanded with sandpaper, the dust is removed and treated with an antiseptic solution.
Now you can apply water-based, oil, acrylic and any other paint.