Wall Preparation for Painting

Wall surfaces must be even and smooth so that paint, applied after all work is complete, lies down evenly and no imperfections or irregularities are visible. There are several key rules to follow to achieve a perfect result.

In a newly built concrete room, you must wait for all moisture to fully evaporate—this may take about thirty days. To check if walls are dry, use a simple method: tape a large piece of polyethylene to the surface for one day. If it darkens or develops condensation, it’s too early to begin finishing work.

Wood, brick, and other building materials release less moisture, so in a new home, you only need to wait for adhesive mixtures to dry before proceeding to the next stages.

How to Prepare Walls with Existing Old Finishing

In a room where work is planned, turn off the electricity supply first, then begin removing old finishes.

• Remove wallpaper with a putty knife; to help it come off more easily, lightly mist with water from a spray bottle a few hours before work. For stubborn spots, use a specialized cleaning solution.
• For oil-based paint, wash with a 3–5% soda solution, then scrape off flaking layers with a metal brush or putty knife.
• Remove water-emulsion coatings with mild acidic solutions applied with a soft brush or sponge.
• For adhesive-based paint, moisten with a 1–2% hydrochloric acid solution, then scrub the wall surface.
• Water-dispersible paints take longer to remove—first, apply old newspapers to the wall like wallpaper, then scrape them off.

After removing old coatings, sand any uneven areas with pumice stone or fine sandpaper. If rust stains are present, wash with water and treat with a 10% copper sulfate solution to prevent them from bleeding through new layers. Greasy stains can be cleaned effectively with a 5% solution of calcined soda. Mold must be washed off with warm water and household soap (removes odor) and treated with fungicides in a half-meter radius around the stain.

Next, assess the overall wall condition: if the surface is flat, perform light sanding first with coarse, then fine sandpaper. If small chunks of plaster have detached, or cracks and chips exist, apply a primer and level the area after drying. If walls are uneven or the plaster layer is old, it’s best to completely remove the old layer using a putty knife. Afterward, wash walls with a soda, ammonia, or soap solution and rinse thoroughly with clean water.

Wall Leveling Before Painting

If walls were completely stripped down to the base after old finishes, they must be re-plastered. Apply a moisture-resistant primer layer to improve adhesion between the plaster and wall. Then, install guide rails (‘maya’) at the most protruding points across the room, and apply a plaster mix until the wall is fully leveled. Commonly used materials include:

• Lime-based mix: a low-strength, highly eco-friendly solution.
• Gypsum plaster: ideal for low-humidity indoor spaces.
• Cement-sand mix: moisture-resistant, strong, suitable for both interior and exterior applications.

If walls are already flat, you can skip plastering. Use one to three layers of spackle to achieve a perfectly smooth surface, free of defects such as chips, cracks, or uneven thickness. Each layer, 0.5–1.5 mm thick, must dry and be sanded before the next is applied. In some cases, a special mesh—called a 'web' made from thin reinforced fiberglass cloth—is used, and only after that is spackle applied.

Each applied layer must dry completely—this is essential. Without proper drying, stains may show through the paint, and the surface will not be perfectly smooth. Drafts and cold air can slow drying and damage the prepared surface, so close all doors and windows after work. Once dry, sand the wall with sandpaper, remove dust, and treat with an antiseptic solution.

Now you can apply water-emulsion, oil-based, acrylic, or any other type of paint.