How to paint a concrete wall ? The steps

You have a concrete wall and you want to renew? Need to brighten up that dull gray concrete surface with a glossy coat of paint? It’s entirely possible. As so often, all you need is time and careful preparation. Because to succeed in your business, that is to say to obtain a beautiful concrete wall that lasts a long time, good preparation, especially of your wall, is essential. The floor of your garage, that of your terrace or the wall of your basement is up to you! If you follow the steps below very conscientiously then you will get satisfactory results no matter what part you are tackling.

In short, how to paint a concrete wall?

  1. Use patching compound to fill any holes, scratches or gouges in the concrete surface.
  2. Thoroughly clean the concrete.
  3. Then let it dry.
  4. Apply special paint, first around the perimeter of your wall and then in the middle. Let dry.
  5. Scrape the places where the paint has not adhered and sand.Apply the second and final coat of paint, then let it dry.

What do you need to paint a concrete wall?

Here are the essential tools and materials you will need to paint your concrete wall:

  • Coating or putty for concrete
  • An electric or sandpaper sander
  • Du phosphate de sodium
  • A brush with metallic bristles
  • A roller for painting concrete
  • Special concrete paint
  • rubber gloves
  • A dust mask
  • Protective glasses

How to paint concrete?

Step 1: Fill hollowed or damaged areas with filler

To start the process, a rather unglamorous step: that of tracking down the slightest hole, the slightest imperfection or crack to fill it with filler in the most careful way possible. Use a suitable filler or putty to fill in any holes and scratches in the concrete. After allowing sufficient drying time, sand the repaired areas until they are smooth.

Step 2: Clean the concrete wall surface

Thoroughly clean the floor or concrete surface using a mixture of phosphate rock and hot water, removing all oil and grease that would otherwise interfere with your paint job. Soak the wall in the solution with a wire-bristle brush. To determine the proper water to phosphate ratio, read the instructions on the package. Phosphate can damage skin and eyes if in contact, so be sure to wear full protective gear.

Step 3: Let the surface dry completely before you start painting the concrete

When phosphate comes into contact with concrete, it reacts. You will likely notice slight bubbles forming on the floor or surface. Let these bubbles continue to “coat” the concrete for about 20 minutes, then hose down your wall, rinsing out the phosphate completely. Let the surface dry for two days before painting. After it dries, run your hand over the concrete. Your wall should feel like sandpaper.

Step 4: Apply paint around the perimeter of the wall

Sweep the area or wipe it with a dry cloth, depending on the orientation of the surface. You are now ready to start painting. Use a paintbrush to apply a first coat of paint on the exterior part of the wall. A regular, medium-sized paintbrush gives you good coverage of corners and edges whether you’re working in an indoor or outdoor space.

Step 5: Continue painting until you cover the entire wall

Then use a paint roller to cover the areas you didn’t brush on. If you’re painting a concrete floor, remember to start on the opposite side of the room, so you end up near a door or another convenient starting point. Let this first coat of paint dry for at least about fifteen hours.

Step 6: Scrape or sand imperfections from the wall surface

Putty knife in hand, scrape off the protrusions that appeared after the first coat dries. Sand any areas where the paint has not adhered. If you make a lot of dust while sanding, consider sweeping again.

Step 7: Apply a second and final coat of paint to your concrete wall

Apply the second coat of paint the same way you applied the first. This time though, press down firmly with the roller, squeezing the paint well so that it gets into the holes it failed to fill the first time. Before you consider the project finished, let the second coat dry for about five days, especially if the painted surface is a heavily trafficked floor.

Here again, you can choose not to carry out this type of task yourself and to call on a professional whose job it is. Its performance will vary depending on the time it takes: should it start with a coat of primer? How many coats do you need? What kind of paint will he use? You can ask for quotes to get an idea of ​​the price of the work.

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