Concrete surfaces, whether internal or external, don't necessarily have to remain a dull, flat shade of gray. This material can be revived and embellished with a few coats of paint. This is a simple and inexpensive operation that most laymen can complete. To successfully paint concrete or another area of masonry, you must first clean and prepare it properly, use the most appropriate paint and wait for the time it takes for it to dry.
Steps
Part 1 of 2: Prepare the Surface
Step 1. Clean the concrete with soap and warm water to remove any traces of old paint
First sweep the area to remove any leaves, debris and dirt. Then remove the old paint or encrustations with a pressure washer or with a scraper and metal brush. Scrape off all the dirt, dirt and scale that is stuck to the concrete. If the stains are now absorbed and don't form a raised layer on the surface, don't worry.
- Tear off any vines, moss, or other live plants covering the concrete.
- The area to be painted must be clean and free of foreign material for good results.
Step 2. Remove oil-encrusted and greasy stains using sodium phosphate; this allows you to prevent the paint from staining later
You can buy sodium phosphate from most well-stocked hardware stores and even DIY stores. You simply have to dilute it in water respecting the proportions indicated on the package and then use it as a detergent on all oil stains. At the end you have to rinse to get rid of any residue. Wait until the concrete has completely dried before continuing with the next steps.
Step 3. Apply some specific cement or putty to repair any damage such as cracks, holes and uneven areas
The surface should be as smooth and even as possible. Cracks and crevices can potentially cause moisture to surface under the paint layer which, as a result, will flake and peel off the concrete. Read the instructions on the dry cement bag for drying and curing times.
Step 4. Seal the surface if it is inside the house
This way you prevent moisture from emerging. The sealant product is expensive, but it is also your best bet to make sure the paint layer does not wear off or peel off too soon once the job is done. Cement is a very porous material, that is, it is able to absorb moisture which over time could rise to the surface and damage the paint. Follow the directions on the sealant package to prepare and apply it.
If the concrete surface is outside, you can skip this step
Part 2 of 2: Painting the Surface
Step 1. Check the weather forecast to make sure you have 2-3 consecutive days without rain before proceeding with painting an exterior surface
You will have to wait for the first coat of color to dry overnight, then apply a second and possibly a third coat. After each layer, the paint must dry for at least 24 hours, so that in the end it adheres perfectly. Plan the job carefully and only start when the weather conditions are favorable.
In some cases, it may take up to 24 hours for the paint to dry completely. This is the reason why it is important to allow yourself a lot of time to finish the painting process
Step 2. Apply a coat of concrete primer using a paint roller
Before you think about color, you need to apply a coat of primer to allow the paint to adhere. The task of the bonding agent is precisely that of guaranteeing good adhesion between the color layer and the surface. Also in this case, follow the instructions on the product packaging to know the installation techniques and drying times.
If you are painting over an old coat of paint or the concrete is on the outside, then you should apply two coats of primer. Make sure the first layer is completely dry before moving on to the second
Step 3. Buy the right paint for your purpose
When it comes to coloring concrete, the best product to buy is wall paint, which is designed to expand and contract based on changes in the temperature of the concrete. It is sometimes sold as an elastomeric paint, or elastomeric coating. Since it is a much denser product than regular paint, you need a high absorbency roller or brush.
Step 4. Apply a thin, even coat using a painter's roller
Start from a corner or from the top if you are painting a wall. Proceed slowly and evenly, spreading the color over the entire surface. You won't need as much paint on each layer as you might think, as you'll need to apply an extra coat or two when the first one is dry. So do not encrust the surface with all the color you have available.
Step 5. Go back to work the next afternoon and apply the second layer of color
When the first has had a chance to dry overnight, you can apply the second. The second (thin) coat of paint is always necessary, but in some cases it is advisable to proceed with the application of a third layer to obtain a more intense and uniform color.
Step 6. Wait for the paint to dry for 1-2 days before stepping on it or placing anything on it
Leave the final coat of color undisturbed for at least 24 hours before bringing objects close to the surface or covering it; in this way you will get a professional and uniform result.
Advice
- Several thin coats of paint form a harder surface than a single thick coat (which will be rubbery).
- The concrete is only painted when it is necessary to cover an existing casting. Fresh concrete should not be painted until the curing process is complete, which typically does not occur before 28 days.
Warnings
- Take all safety precautions when using sodium phosphate, as it is dangerous for the eyes, skin and lungs.
- If you need to paint a concrete floor, use an additive to mix directly into the paint which makes the surface non-slippery. This way you prevent anyone from falling.
