Masonry Magazine October 1994 Page. 22
Colored Mortars and Cleaning Solutions
Colored mortars are used. Manufacturers of proprietary cleaning solutions often provide different products for application on projects using dark-colored mortars than for projects using light- or white-colored mortars. The manufacturer of the cleaning solution and the manufacturer(s) of the colored mortar materials should both be consulted prior to selecting a cleaning procedure or solution. The acceptability of cleaning procedures should then be evaluated as indicated in the previous discussion about planning.
Masonry constructed using concrete masonry units usually requires no further cleaning than what is outlined in the construction section of this document. Mortar color is typically similar to that of concrete block. In addition, the block masonry surface is often either painted or plastered (stuccoed) to provide the desired finished appearance. If further cleaning is required where colored or architectural units are used, the manufacturer of those units should be consulted before selecting a cleaning procedure. Acidic cleaning solutions can dissolve cement paste from the face of concrete masonry units altering the appearance and texture of the unit surface.
Careful consideration must be given to unit characteristics when selecting a cleaning procedure for masonry constructed with clay masonry. Once again, the specific manufacturer of the unit used in the masonry construction should be consulted for cleaning recommendations. Generally, a range of cleaning options is appropriate for various types of units. Bucket and brush cleaning with a dilute acid or proprietary cleaning solution can be used on red brick and red flashed brick. High pressure water cleaning may also be used on red and red flashed brick but it is not recommended on sand finish or surface coated brick. Dilute hydrochloric acid (muriatic) cleaning solutions, including proprietary cleaners containing hydrochloric acid, are not to be used with brick that contain manganese or vanadium.
Construction
Good construction is integral to obtaining a clean masonry job. Excessive mortar smears are often a symptom of poor overall workmanship. They should trigger closer scrutiny of the masonry construction by mason contractor's project supervisor or other members of the construction management team. An accomplished mason will construct masonry having a minimum of mortar droppings or smears on the face of units. In addition to developing the skills required to construct masonry walls that are essentially free of mortar droppings, the mason can take the following steps to minimize cleaning requirements:
Keep Units Clean: Protect stored units from mud, dirt, or other contaminants.
Cover the Bottom: Use straw, sand, or plastic to protect the base of the wall from rain splashed mud and mortar splatter.
Minimize Mortar Droppings: Carefully cut excess mortar off with trowel as units are laid. Minimize amount of mortar droppings and smears on face of wall.
Time the Tooling: Allow mortar joints to stiffen to "thumbprint hardness" before tooling. Tooling at the proper time will help to minimize mortar smears.
Trim with Trowel: After tooling, use trowel to trim mortar burrs off flush with the face of the wall.
Brush After Tooling: Lightly brush dust and loose mortar from surface of masonry using a soft brush.
Clean as-you-go: Remove mortar protrusions or droppings from the face of the masonry. Allow mortar to achieve an initial set prior to removal to avoid smearing mortar into masonry, but do not leave mortar droppings on masonry for an extended time as they will then become more difficult to remove. Non-metallic scrapers may be required to avoid damaging the surface of clay masonry units or architectural block units. Often a small piece of a similar unit will function as a satisfactory scraper.