Because of their versatility and relatively low cost, concrete blocks are a popular building material. They are widely used for exterior walls, retaining walls and planter boxes. The main drawback of concrete block is the fact that they can be unattractive. Fortunately, there are a variety of acrylic concrete stains on the market. With a little bit of preparation and work, you can use these stains to turn that boring gray wall into a thing of beauty.
Preparing the Concrete Wall
Clean the surface. You can use a concrete cleaner for this, or a pressure washer if you have access to one. You want to remove grime, dirt or other contaminants that could prevent the stain from properly penetrating into the concrete's surface.
Test for absorbency and texture. Concrete should be rough and absorbent before it is stained. You want the concrete blocks to have a consistency like 120-grit sandpaper. Water sprayed onto the concrete block should soak into it. Typically concrete blocks are rough and absorbent. However, if your blocks are smooth, or resisting water, you will need to etch them with a concrete etching solution.
If you need to, apply the concrete-etching solution to the blocks. Let it sit on the surface for 30 to 45 minutes. This should open up the pores of the concrete and give it some texture.
After etching, use a concrete-cleaning product to neutralize the etcher and to remove any concrete powder that was generated during the etching process. Rinse thoroughly and allow the concrete to dry for 24 hours prior to staining.
Applying Stain to your Concrete Block Wall
Use a pump-up sprayer to apply the stain. Adjust the sprayer's nozzle so it creates as wide a spray pattern as possible.
Start in one corner and work your way out from there. You want to use a circular, sweeping movement in order to give the stained concrete an organic feel. If you apply the stain in straight rows, you'll see straight rows in the finished product.
Move quickly. Spray just until the concrete begins to wet and then move along. On a vertical application you want to avoid applying so much stain that it runs down the surface. You will see these streaks in the finished job.
On a wall it is a good idea to apply multiple light coats, in order to avoid the risk of over-application.