How to Stain Concrete Blocks

Ensure your concrete blocks are clean and free of grease, dirt and other substances. Sweep away any loose debris and scrub the blocks with trisodium phosphate cleaner in a well-ventilated area. Be sure to wear waterproof gloves and safety goggles, and follow the manufacturer's instructions. Cracked concrete will cause inconsistencies in the stain. If there are deep cracks, cover them with a thin cement-based overlay. To remove caulking from the blocks, use a putty knife. Repeat cleaning with a trisodium phosphate cleaner, then rinse the concrete block with water. If your concrete is ready to stain, the water will penetrate its surface when applied.

Test your stainer on a part of the block that will be hidden. This will allow you to preview the final color before staining the entire block.

Stain the concrete block following your preferred stainer's instructions (the process varies by type of stainer and brand). According to the Concrete Network, new concrete needs to be cured for 30 days prior to staining. Ensure the moisture level is consistent and use a high quality paintbrush to add the stain. Apply gentle pressure, working from an unstained area toward a stained area to help minimize the appearance of brush strokes.

Allow your stained blocks to dry in a safe, ventilated area. Drying times vary by individual stainer. After the stain dries, residue will appear. To remove this coating, combine 1/2 cup of baking soda with a gallon of water and use it to scrub the surface and then use a wet/dry shop vacuum to suck up the residue. After the residue is gone, rinse the blocks completely with water and let them dry for two days.

Apply a surface sealer to the newly stained concrete. Concrete Network recommends using acrylic-based sealants if the blocks will be kept outside.