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Phone: (425) 828-0433 |
Cleaning, Restoration, And Maintenance Cleaning Masonry Construction
1) Cleaning New Buildings
2) Removal of Stains
3) Cleaning Existing Masonry
4) Cleaning Failures
5) Check List For Cleaning Procedures
6) Guide Specifications For Masonry Cleaning
1. Cleaning New Masonry
Why Clean? The reasons for cleaning any building must be considered carefully before arriving at a decision to clean.
- Is the cleaning being done to improve the appearance of the building or to make it look new? The so-called "dirt" actually may be weathered masonry, not accumulated deposits; a portion of the masonry itself thus will be removed if a "clean" appearance is desired.
- Is there any evidence that dirt and pollutants are having a harmful effect on the masonry? Improper cleaning can accelerate the deteriorating effect of pollutants.
- Is the cleaning an effort to "get your project started" and improve public relations? Cleaning may help local groups with short term fund raising, yet cause long term damage to the building.
These concerns may lead to the conclusion that cleaning is not desirable -- at least not until further study is made of the building, its environment and possible cleaning methods.
Repositioning the scaffolding board which is
nearest the wall at the end of a day's work helps
prevent dirt from splashing on the wall.
1.1. Bucket and brush hand cleaning. This is probably the most popular but most misunderstood of all the methods used for cleaning brick masonry. Its popularity is due to the simplicity of execution and the ready availability of muriatic acid and proprietary cleaning compounds. A recommended general procedure using detergent, acid, or proprietary compound solutions is as follows:
1.1.1. Select the proper solution.
a. Hydrochloric acid dissolves mortar particles. Mix a 10% solution of muriatic acid (9 parts clean water to 1 part acid) in a nonmetallic container. Pour the acid into the water. Do not allow metal tools to contact acid solutions.
b. For proprietary compounds, make sure that the one selected is suitable for the brick and follow the manufacturer's recommended dilution instructions. Many proprietary cleaning solutions perform in a satisfactory manner for their intended cleaning jobs. However, their formulae are not generally disclosed and may be subject to change. It is suggested, therefore, that each product being considered be sample tested on a panel or inconspicuous wall area and judged on a trial basis before being used.
c. Detergent or soap solutions may be used to remove mud, dirt and soil accumulated during construction. A suggested solution is 1/2 cup dry measure (0.14 L) of trisodium phosphate (Calgon or equal) and 1/2 cup dry measure (0.14 L) of laundry detergent (All or equal) dissolved in one gallon (3.9 L) of clean water.
d. For very difficult mortar stains on glazed brick and tile, use no more than 1 part high grade acid (chemically pure) to 25 parts clean water.
1.1.2. Schedule cleaning last, if possible. Mortar must be thoroughly set and cured. Prolonged time periods elapsing between the completion of the masonry work and the actual cleaning should be avoided when possible. It has been observed that mortar smears and splatters left over a long period of time (6 months to 1 year can cure on the wall surface and become very difficult to remove. If this condition occurs, there is the temptation to mix acid solutions stronger than recommended in order to dissolve tightly bonded mortar particles.
1.1.3. Dry clean. Remove larger mortar particles by hand with wooden paddles, and non metallic scrape hoes or chisels. Acid solutions, no matter how effective, cannot be expected to completely remove or loosen large particles.
1.1.4. Protect metal, glass, wood, limestone and cast stone surfaces. Mask or otherwise protect windows, doors, and ornamental trim from acid solutions.
Pre-soaking the masonry work is
important in the cleaning process.
1.1.5. Presoak or saturate the area to be cleaned. Flush the wall with water, from the top down. A saturated brick masonry wall will not absorb dissolved mortar particles. The area immediately below should also be saturated in order to prevent absorption of the cleaning solution.
1.1.6. Starting at the top of the wall, apply the cleaning solution. Use a long handled stiff fiber brush or other type as recommended by the cleaning solution manufacturer. Allow the solution to remain on the wall 5 to 10 minutes. For proprietary compounds follow the manufacturer's instructions for application and scrubbing. Wooden paddles or other nonmetallic tools may be used to remove stubborn particles. Do not use metal scrapers or chisels. Metal marks will oxidize and cause staining. When cleaning glazed brick or tile do not use metal cleaning tools or brushes.
1.1.7. Clean a small area, preferably not more than approximately 20 sq. ft (1.9m2). The size of the "wash-down" area should be determined in advance after a trial run. Heat, direct sunlight, warm masonry and drying winds will affect the drying time and reaction rate of acid solutions. Ideally, the cleaning crew should be just ahead of the sunshine, to avoid rapid evaporation. This will also permit the crew to examine their work for initial results.
1.1.8. Rinse thoroughly!! Flush walls with large amounts of clean water from top to bottom before they can dry. Acid solutions generally lose their strength after 5 to 10 minutes of contact with mortar particles. Failure to completely flush the wall of cleaning solution and dissolved matter from top to bottom may result in the formation of "white scum."
The NW Masonry Guide Table of Contents
Masonry Institute of Washington
Washington State Conference of Mason Contractors
