To use it, you must have metal with no clear coating on it. Acetone or stripper will remove the coating. Rub the piece down with #0000 Steel wool, and clean it well with paper towels and acetone making sure you do not touch it with your oily fingers. You can then brush on the darkening solution or soak the parts in it until they turn black in color. They are then rinsed with water, and color adjusted with some dry #0000 steel wool rubbing the black off until you get the look you want.