To clean or remove scale, wet the area (walls, bricks etc) thoroughly with water and mix 1 part Hydrochloric Acid with up to 10 parts water. Apply the solution with a broad brush and then rinse off with water once chemical reaction (frothing) has ended. If the scale or stain is persistent, repeat the process or apply directly some of the undiluted product and then rinse off with water. To clean toilets, apply the product undiluted in the bowl, close the lid and empty the tank.
Since this is a very powerful product, we strongly recommend to follow some few basic safety instructions: Do not ever apply on metals. Avoid contact with skin or eyes, avoid breathing vapours, wear suitable protective clothing, gloves and eye/face protection when using this product. Alwas add acid to water, never add water to acid.