Painting a Concrete Wall
Before you paint a concrete wall, it is not necessary to have serious professional skills in carrying out repairs. It is possible to cope with the task yourself if you use the advice and act according to the instructions. Painting walls – is one of the most budgetary options for finishing, and the ability to do without the services of professionals reduces costs by about half.
Choice of material
Choosing paint for concrete walls is not difficult, although the choice of finishing materials today is very large. Guided by the conditions in which the future coating will be used. By its technical characteristics, compositions for internal works are very different from those with which the painting of facades is performed. Consider the options.
Oil-based materials are widely used for finishing concrete walls outside. For interior work, other compositions are usually used that are less toxic and do not have such a pungent unpleasant odor, but oil-based or alkyd paints can also be used if desired.
- Very low cost,
- High resistance to moisture and other atmospheric phenomena, the durability of the coating,
- Easy care (easy to clean, not afraid of cleaning agents).
In addition to the pungent smell, you can note the long drying time (not less than a day), low elasticity (the coating cracks when the wall shrinks), and unstable color (the olive in the composition eventually turns yellow).
Water-based emulsions and dispersions are suitable for painting concrete walls. These materials have practically no toxic components in their composition. Water-based paints are usually used for interior finishing works, and some types of water-based paints are produced specifically for covering facades. The purpose of the composition is always indicated on the label.
- ease of application,
- no smell,
- short drying time (a few hours),
- the possibility of self-tinting.
The cost of these materials is higher than oil-based analogs, but still quite affordable.
The material is used for various kinds of finishing works, including for painting concrete walls inside and outside. Manufacturers of quality acrylic paints always make labels on the packaging, such as: “for facades”, “for ceilings” or “for walls”. When choosing, pay attention to these specifications. Such paints are also used for artistic painting of walls and euro fences.
- environmental friendliness,
- resistance to mechanical stress,
- water vapor permeability,
- color stability,
- the possibility of obtaining any shade,
- the elasticity of the coating.
These paints can not be called cheap, but the price-quality ratio has made them very popular in the market of finishing materials.
Silicate paints use liquid glass as a base. The resulting coating is extremely strong, which allows the use of silicate paints in the finishing of concrete facades.
- Resistance to chemical attack (reagents, acid rain),
- Color stability,
- Fire resistance,
- Biological resistance (prevent the appearance of mold and other microorganisms).
It should be noted that such a coating is not only resistant to abrasion, but it is also virtually impossible to wash off. Protective properties are very high. There are toxic components in the composition, so when working with silicate paint, it is important to protect the respiratory organs.
For exterior finishing is suitable for rubber paint on concrete; epoxy-based material is often used to cover concrete floors, it is not afraid of temperature changes and other weather phenomena. Fire-retardant paints protect concrete walls from destruction in a sudden fire and textured or texture paints are useful for original decorative furnishings.
Working with the surface of a concrete wall
When going to paint a concrete wall, determine if the surface needs restoration or ordinary smoothing. A battered and cracked wall will have to be repaired in any case, but the new and flat can be painted, pre-painted only primed if you like the roughness characteristic of a concrete slab.
Note: a new concrete wall can be painted not earlier than one month after its construction.
The preparatory phase
Consider the most labor-intensive option. Let’s assume that the wall is already “not the first freshness”, it has an old coating, cracks, chips and other damage. Here are the instructions, following which you will be able to prepare the concrete wall for painting.
The layer of old paint must be removed, especially if it is already worn, peeling in places or bloated. Use a trowel, scraper or chisel. These tools can effectively clean a small area.
If the surface is large (or there are several walls), use a power tool. A grinder or drill with an attachment in the form of a stiff iron brush, abrasive wheel, drill bit or chain will speed up and facilitate the process of cleaning the wall from the old coating. Prepare for plenty of construction dust and debris, and don’t forget your face mask and goggles.
Removing paint from concrete, using a construction hair dryer, is very time-consuming because it is difficult to heat a slab of this material to the desired temperature.
Special paint removers (rinsers) work effectively. To remove oil-based paints, alkyd or nitrocellulose compositions, you should use a liquid based on an organic solvent. Older water emulsion or dispersion can be handled very well with an alkaline cleaner. Any type of remover has an unpleasant odor and harmful components in its composition, so you have to protect your respiratory system.
Sandblasters remove old paint from the surface well, but not everyone has such a device.
When the surface is cleared of paint, it must be inspected for mold, efflorescence or grease stains. To cope with these troubles will help antiseptic solutions, hot soapy water, soda ash and copper sulfate (concentration of 15%). The wall should be thoroughly treated and dried.
Priming and leveling
Any finishing compound can be applied to a concrete wall only after it has dried completely. You can check the moisture level with a piece of polyethylene film taped to the surface around the perimeter with tape. If after 24 hours condensation has accumulated under it, it means that the humidity is high, and you have to wait some more time.
Now it’s time to apply fluid (a solution of salts and acids); this product is indispensable for walls made of concrete, it penetrates deep into the structure of the material, strengthening it from the inside.
Next, the surface is smoothed with putty. Use a trowel and a construction rubbing tool. When the material is completely dry (see the instructions on the package), work the wall with sandpaper. Finishing putty is applied to make the surface perfectly flat. The final sanding is done with fine-grit sandpaper.
The priming mixture is applied to a clean and smooth wall. Choose a solution with antiseptic in its composition. Consider also the type of paint for the upcoming finish; the primer must match it (it is even better to buy means of the same manufacturer).
Apply the liquid with a paint roller or a broad brush. It is good if you put it in two or three layers, letting each of them dry. Primer is necessary to create a strong bond (adhesion) of paint with the surface, protecting the wall from mold. In addition, this action allows you to significantly reduce the consumption of paint material.
Preparing the surface for further painting
Thoroughly mix the paint until the product is uniform. Use a construction mixer or a drill with an appropriate attachment. The following tools are needed for the job:
- paint roller and brushes,
- paint tray
- paper tape.
Cover baseboards, door jambs, and window frames with painter’s tape to mark the boundaries of the area to be painted. Start with areas that are hard to reach with a paint roller: corners, joints with the ceiling, surfaces around electrical outlets, and switches. Work them with a brush.
Now pour the paint into the cuvette and soak up the paint coat on the roller. Start applying the material to the wall from top to bottom, rolling the tool in different directions (up and down, right and left) alternately. In this way, paint square by square.
Allow the first coat to dry well before applying a second one. Two coats are usually enough to achieve a high-quality, presentable finish.