Brick can be cleaned by mixing muriatic acid and water, brushing or spraying the mixture on the bricks and then rinsing it off. Avoid any skin contact with the mixture.
Muriatic acid is a very strong acid that is used in masonry work. Homeowners must follow all safety precautions when using muriatic acid. According to the experts at Natural Handyman, muriatic acid can damage anything, including skin.
It is often easier to spray the muriatic acid and water solution onto brick walls than it is to try to use a scrub brush. Purchase a cheap plastic sprayer and put the water in first, in the amount instructed on the acid's container. . Never put the acid in first; it will eat the plastic immediately.
Make sure to wear rubber gloves and if the wind is blowing, full-body protection. Spray the brick wall with water before applying the acid solution. Let the acid soak for about 10 minutes and, if necessary, use a stiff brush on difficult areas. Rinse with a solution of 1-cup ammonia to 1-gallon water to neutralize the acid. The brick should now be clean until the next annual cleaning.