Painting concrete provides a clean, fresh appearance, as shown in Figure 1. Painted concrete is easier to clean, spills wipe-up easier and the paint provides a level of protection to the surface.
Figure 1 - Painted concrete patio
As with many home improvement projects if you want a quality project the preparation work is more important than the finishing work – in this case the actual painting of the concrete.
Before you paint any concrete you should perform a test to ensure that you do not have a moisture problem beneath the concrete. Hydrostatic pressure is moisture that is below the concrete that is trying to escape through the concrete. The best concrete finishes in the world will not adhere to concrete that has a moisture problem. So before you invest in quality concrete paint you should perform a simple test to check for hydrostatic pressure below the concrete you are planning on painting.
Remove the dust, dirt and grime from a 1 foot area of concrete. Use duct tape to tape a square foot of plastic, a plastic garbage bag works well, to the cleaned area of concrete. Wait 24 hours and remove the plastic. If the concrete that was under the plastic is damp or if there is moisture on the underside of the plastic you will have a problem getting the paint to adhere to the concrete.
Note: You do have some finishing alternatives if you have a moisture problem. You can use an acrylic concrete sealer although most concrete sealers have a limited life – approximately 6 months. You can also use a concrete stain. Concrete stains do not seal the concrete; they allow the concrete to breath and release any moisture rising to the surface.
Additional information on staining concrete.
Types Of Concrete Paint:
There are three basic types of concrete paint available.
- Latex Based Concrete Paints:
- Oil Based Concrete Paint:
- Epoxy Concrete Paints:
Although latex based concrete paint is the most commonly used concrete paint, primarily because brushes and rollers can be cleaned-up with water it does not create the hardest or most abrasion resistant surfaces on concrete. Latex breathes and will allow moisture to escape which helps to prevent the paint from blistering and peeling. It has a high level of adhesion to concrete.
Oil based concrete paint is a good choice for outdoor concrete painting applications such as patios, porches, driveways and steps. It produces a much harder and is much more abrasion resistant finish than latex paints. Oil based concrete paint can also be purchased with a high gloss if that is what you desire in a finished appearance. Oil based paints require the use of mineral spirits for clean-up.
If latex based concrete paint is the Chevrolet, then oil base concrete paint would be the Cadillac and epoxy concrete paint would be the Ferrari! Epoxy paint is the longest lasting of the three types of concrete paint. It bonds exceptional well to concrete and its resistance to abrasion is superior to latex or oil based concrete paints. Although it is a suitable finish for both indoor and outdoor concrete, it is highly recommended for basements where dampness is a problem.
Note: As a general statement wait at least 90 days before painting freshly poured concrete. Check the specific instructions on the paint you are planning on using for information on the wait time for freshly poured concrete curing times.
Note: Concrete paint is not a product that should be used to
refinish the surface of the concrete. If your concrete is flaking, blistering or cracking, those problems should be taken care of before attempting to apply a painted finish.
Note: Most of today’s quality concrete paints have a mildew preventative blended into the formula. This helps to prevent the growth of mildew and other bacteria on the painted surface of the concrete. It is highly recommended that concrete paint used in basements have a mildew preventative in the paint formula.
Instructions For Painting Concrete:
Note: Always follow the specific concrete paint manufacturer’s instructions for both surface preparation and methods of application.
- Any paint that is currently on the concrete that is flaking, peeling and/or blistering must be removed. In most cases a pressure washer will remove the vast majority of flaking, peeling and blistering paint. However, in some cases it may be necessary to use a sand blaster or grinder to remove paint from some of the areas. Sand blasters are available from most equipment rental facilities.
- The concrete must be clean or the paint will not adhere to it. This means removing not only the surface layer of dust and dirt, but removing any rust, oil, grease or other stains that might exist. There are numerous commercial cleaners available to eliminate grease and oil or you can try our homemade grease and oil removal cleaner.
- For the best adhesion you can etch the concrete using a diluted solution of 1 part muriatic acid and 3 parts water. Evenly spread the diluted muriatic solution over the concrete. Allow the muriatic acid solution to sit for 15 minutes and then wash down the concrete with fresh water.
- Once the concrete surface is clean and dry, you can commence painting.
Caution: Muriatic acid not only eats concrete it will eat skin and clothing. Make sure you use protective goggles, rubber gloves and proper clothing when using the solution. It is also toxic and should only be used in well ventilated areas. As well, before using the solution ensure that you can in fact wash down the concrete without damaging plants or other items.
Use a latex concrete paint primer that is recommended by the manufacturer. In many cases the latex concrete paint can be used as its own primer with a second coat as a finish.
Oil based concrete paint is much thinner, in consistency, than a latex paint and for that reason you should use an oil based concrete primer that also contains a filler. The use of a filler/primer will create a smoother finish on the second coat.
Epoxy concrete paint comes in two parts that are mixed together before they are applied to the surface of the concrete. In most cases the epoxy concrete paint does not require a special primer or undercoat. Use three coats of epoxy concrete paint for a long lasting finish, that will stand-up to a great deal of wear and tear.
Note: In all cases, unless the manufacture states otherwise, you can use a medium to long nap paint roller, and synthetic brushes to apply the concrete paint.
Note: Flaking, peeling and blistering of concrete paints, as shown in Figure 2, are usually caused by inadequate preparation of the surface of the concrete prior to application of the new concrete paint.
Figure 2 - Flaking, peeling and blistering of concrete paint
Note: As the surface of the concrete must be clean and free of dust and dirt it is important that the painting of the concrete take place as soon after it is cleaned as is possible. Waiting a week or two between cleaning and painting is a recipe for paint adhesion problems.