More in Outdoors
Begin by removing dirt, grease or mildew with a non-residue cleaner and a stiff-bristled brush. For stubborn oil and grease stains, a pressure washer and a degreaser may be needed.
Put on boots, gloves and safety goggles with a respirator before handling the muriatic acid. Mix one part acid into four parts water in a plastic sprinkling can. Wet the concrete surface once again and soak any surrounding grass or shrubs. Then sprinkle the acid solution onto the concrete. It should bubble on contact. Allow the acid solution to etch for 20 to 30 minutes to neutralize the concrete's alkalinity, and then remove the acid with a broom and plenty of water.