Staining concrete is a cost effective way to update a floor or landscape. Stain concrete any colour you choose, and it will last for a long time with careful preparation. Concrete is a porous material that readily accepts stains as long as it has not been previously sealed or buffed. You must clean and sand a sealed or buffed area of concrete that you want to stain before the stain will adhere. Staining concrete is a multiple-step process that takes up to seven days to complete.
Test the concrete for water absorption by sprinkling water on it. Water must absorb into the concrete before you can apply the stain. Standing water means that there is a sealer present, so you must sand the concrete.
Repair all cracks with a ready mix concrete patch. Follow the instructions for mixing the concrete. Fill the cracks with a concrete trowel until they are smooth and level with the floor. Allow the patches to dry overnight.
Sand the entire concrete surface with the walk-behind buffer to remove the concrete sealer. Follow the instruction guide for using the sander that is printed on the machine. Most walk-behind sanders are self propelling and only require you to guide it across the floor.
Sweep up all sanding dust with the shop vacuum, and perform another water test by sprinkling water across the concrete. Sand all areas again that do not readily absorb the water.
Mix 1 part TSP (trisodium phosphate) to 4 parts water in a 5-gallon bucket. Spread the solution across the concrete with a mop. Use the wet vacuum to suction up the cleaning solution, and rinse the concrete with clean water. TSP removes grease, stains, dirt and grime from the concrete.
Put on all protective clothing before applying the stain. Concrete stain is acid based and causes serious eye injuries, skin irritations and respiratory problems.
Cover all baseboards and adjacent flooring with plastic for interior applications. Use painter's tape to hold the plastic in place. Lay plastic along driveways and sidewalks to catch runoff.
Thoroughly stir the concrete stain with a wood stir stick, and fill the pump-up sprayer with the stain. Set the pump-up sprayer to a medium-mist pattern. Begin spraying the stain at one side of the concrete, and work your way to the other side. Spray a 3-foot wide path, and immediately scrub the stain into the concrete with the stiff broom. Spray stain back over the same path to remove the bristle marks. Continue this process until the entire concrete surface is covered with stain. Allow the stain to dry according to the manufacturer's instructions, and apply a second coat of stain using the exact same process.
Neutralise the acid stain by mixing 1 cup of baking soda to 5 gallons of water. Begin mopping the solution onto the floor, and scrub it with the stiff broom. Work your way across the concrete until the entire surface has been mopped with the solution. Rinse the concrete with clean water immediately after mopping with the baking soda and water solution. Allow the concrete to completely dry.
Apply a coat of interior or exterior clear concrete sealer with the paintbrush and roller. Use the paintbrush to cut in edges near walls on interior applications. Roll an even coat of sealer across the concrete by using a roll-and-lift method. Place the roller to the concrete with sealer on it, roll the sealer away from you and lift the roller. This pattern will eliminate roller marks. Allow the sealer to dry overnight, and apply a second coat. When the sealer is dry, the concrete is ready to be put back to use.
Concrete that will not absorb water after sanding cannot be stained. To accept stain, it requires resurfacing without a sealer. Rent a walk-behind buffer at a home supply store.