This story shows how to apply acid stain.
Working outdoors or in a well-ventilated room and wearing goggles and gloves, pour the acid stain into a plastic-body sprayer. Read the manufacturer's directions to determine if the stain should be diluted for a hand-troweled floor. You may also want to dilute the stain with water, depending on the intensity of the color desired. (Experiment with the color in an inconspicuous area.) Hold the wand about 18 inches above the surface of the floor as you apply the stain. Let dry 1 hour, spray on a second coat, and let dry.