This project was completed this week by Peerless Pressure Washing. All of the bricks on the property had calcite and rust stains that had to be removed. We used a combination of chemicals to remove the stains and brighten the bricks.
In preparation for the chemicals used to remove the stains, all of the surrounding grass and vegetation must be watered in. Once all of the surrounding areas are prepared, we begin to apply the stain removing chemicals. Pressure washing brick is not what it seems. You never want to use high pressure to remove the stains. This will further compound the problem with efflorescence.
Calcite stains must be removed with muriatic acid. A solution of 1 gallon water to 1 gallon acid is applied to the bricks using a chemical pump. Once the acid is applied, you will notice the reaction taking place. Before rinsing, a stiff bristled brush is lightly ran across the thicker heavier stains. This step may or may not have to be repeated depending upon the severity of the calcite buildup.
The bricks are then pressure washed with very low pressure. A 2520 tip was utilized to rinse the acid. This is a high flow tip designed for rinsing. Never use high pressure washing for brick cleaning.
Once you have cleaned the bricks of the calcite stains, it is time to remove any rust stains. You can also brighten the bricks at this time killing two birds with one stone. HF or hydrofluoric acid is just what the doctor ordered for this step. The HF will remove the rust stains and also brightens the bricks at the same time. This acid does not need to be brushed. Our crew applied the acid with our down stream injection system on our pressure washer. With the raw chemicals we purchased and a little math this gave us the correct ratio needed.
Whenever using acids with pressure washing you must take these steps at the minimum. First always wear eye protection when using any chemicals while pressure washing Tampa homes. Black nitrile gloves were utilized whenever handling any tools used during the application and during the application of chemicals. If a chemical suite is not available make sure all areas of the body are covered. All clothing used are to be removed at the job site and placed in plastic garbage bags, including boots.