The elements of cleaning

New Construction

• Glazed Brick: Glazed brick is hard and does not easily absorb the mortar, so often you can use relatively high pressure, little cleaning agent, and hot water to remove mortar and its film.
• Standard Red Brick: New red brick is generally hard but porous. Therefore, you will probably want to use high water pressure, a masonry cleaning chemical, and hot water.
• Colored Brick: Colored brick involves additional challenges, because the chemicals that provide the color and react with the cleaning agent to give unwanted color inconsistency. You will want to use high water pressure, a cleaning agent specifically made for cleaning colored brick, and hot water. Because the specialized cleaning agent is less powerful than regular cleaning products, you may need to use more to maintain an acceptable level of productivity.
• Cement Brick: Though cement brick is hard, the material will etch and expose some aggregate if the cleaning agent contains acid. If the color is not embedded into the brick, you will also get some color change with the etching. The difficulty is that you need some acidity to remove the mortar, while minimizing the effect of the acid on the cement. Using high-pressure hot water and minimizing the use of a cleaning agent is best. The usual solution to the dilemma is to try to minimize the etching, while making it consistent over the entire surface. Getting the architect’s agreement on the desired appearance is critical.
• Cement Block: Block has some of the same problems as cement brick; you need acidity to remove the mortar, but it will etch the surface, exposing aggregate. For this cleaning situation you may want to increase the hot water pressure, either by holding the wand closer to the surface than you normally would or using a more aggressive rotating nozzle and an appropriate cleaning agent.
• Raked Surface Brick: A raked surface, because it will absorb more mortar, will require an increase in the cleaning agent with high-pressure hot water.
• Sand Faced Brick: To maintain the sand face, you will need to greatly reduce the agitation by reducing water pressure, increase the cleaning agent quantity and using hot water.
• Faux Stone: Typically, faux or veneer stone is manufactured by pouring concrete into a variety of molds, and then coloring each piece. The coloring is painted on the surface, so using any amount of agitation and cleaning agent may deface the stone. A present, manufacturers do not have any recommendations for cleaning it, other than very low-pressure water to remove any environmental discoloration.
• Cast Stone: Care should be taken to avoid the need to clean cast stone. This should be done by covering the pieces with plastic to avoid getting mortar on the surface. Any cleaning agents that will remove mortar will etch the surface of the cast stone, changing its appearance and streaking it. Therefore, if the cast stone is used with materials that will be cleaned, the cast stone must be protected from the runoff.
• Natural Stone: Certain stones, such as sandstone and limestone, will not tolerate cleaning with acid-based cleaners as the acid will dissolve naturally occurring elements in the rock. Moderate pressure can be used with specialized non-acidic cleaning agents and hot water.

Restoration and Rehabilitation

Conclusion

• Increasing the temperature of the cleaning agent and the surface to be cleaned, either by using hot water and heating the cleaning agent with the water or creating friction by brushing, will increase the power of the cleaning agent. If you want the cleaning agent to be less powerful, decrease the temperature or use less.
• Generally, agitation is accomplished either by water pressure or manpower using brushes or even rags. It sure is easier to let water pressure do the job, if the surface will tolerate it.
• Chemicals represent the greatest variable cost in cleaning, so it is important to identify the chemical with the right balance of power and cost. There are seemingly unlimited choices in cleaning agents. Sometimes the choice comes down to what you’ve had the best experience with and what is most available to you. Sometimes the choice is made by the designer, who perhaps made the choice based on what specification happens to be most available on his computer. Other times, it is important to choose the right formulation for the job at hand and to vary the amount of agent being used to get the job done in an acceptable amount of time and at an acceptable cost.