Do not use on natural marble, stone, terrazzo, polished or anodized aluminum, metallic or painted surfaces, colored grout or counter tops. May etch some older or worn porcelain tubs and sinks or ceramic tile. If in doubt, test hidden areas first. Avoid contact with wood, fabric and wallpaper. Wipe up spills immediately and rinse with water. Not for use on food contact surfaces. Do not use on cookware, coffeemakers, tea kettles, humidifiers and washing machines.