Masonry Magazine April 1989 Page. 18
In general, these materials are available in two types of solutions: water-based solutions and solvent-based solutions. In nearly all instances, better penetration and better performance is attained using solvent-based solutions.
It should be stated, however, that when the proper types of these materials are properly applied under the right conditions, they will perform quite satisfactorily, and at a rather attractive initial cost (15 cents to 25 cents per sq ft of wall surface, as opposed to $1.00 to $1.75 for tuck pointing). It must be considered, however, that re-treatment will probably be required periodically, usually in three to seven years although some specific solutions will last longer.
CONSIDERATIONS
As previously stated, under specific circumstances and conditions, some of these materials perform quite satisfactorily. The obvious problem is to determine when, where and how to use these sealing materials and what materials to use. Following is a list of suggestions, conditions and considerations to assist in making this decision:
Inspection
Prior to considering any applications to a troubled brick masonry wall, a careful and thorough inspection should be made of the areas involved. This inspection should determine the condition and suitability of: caps and copings, flashing, weep holes, caulking or sealant joints, mortar joint condition, and general execution of details. Very often this type of examination will identify the source of the problem and preclude further consideration of colorless coatings.
All potential problems or deficiencies identified by the inspection should be carefully repaired or corrected, including: clearing of weep holes; removal of defective caulk or sealant, cleaning, priming and replacement; cutting out and tuck pointing of incompletely filled, cracked or distressed mortar joints; repair of any possible roofing problems; and replacement of cracked joints in caps and coping with suitable elastic material. After this work has been completed and inspected for correctness, it is advisable to wait a period of several months to determine if other steps are required. Many times the trouble will be corrected by these repairs and further consideration of coatings may be dismissed.
Check List
The following check list is recommended for use in considering the appropriateness of applications of colorless coatings. Its use does not guarantee satisfactory performance, but will greatly enhance the probability thereof. To ensure a high probability of acceptable performance, all of the conditions on the check list should be satisfied.
1. All obvious cracks, poorly filled mortar joints and/or other openings in the face of the brick masonry must be cut out to a depth of 3/8 to 1/2 in. and properly tuck pointed with a suitable prehy
2. All windows, copings, sills and other joints between brick masonry and other materials must be cleaned, primed and caulked with a good grade of elastic sealant; i.e., silicone-rubber, polysulfide base, etc.
3. There should have been no efflorescence or, at the maximum, only a minor occurrence of efflorescence on the brick masonry to be treated.
4. The brick units from which the wall is constructed must be of excellent quality. If not, they may suffer spalling or disintegration as mentioned above. It is suggested that extruded units be of grade SW, without the waivers permitted in the specifications, and molded or dry press units be of grade SW in accordance with the specifications. In addition, the units should be essentially free of face cracks, checks or other damage before any treatment.
5. The wall must be fairly clean and dry at the time of application. Heavy coatings of city dirt and/or dampness will interfere with proper penetration of the sealer solution and result in poor performance and shorter life.
6. The sealer material should be that of a well known manufacturer who has been in business for a reasonable length of time. It is possible to get these materials from very small organizations that have little or no investment nor any sense of responsibility to their customers. It is suggested that a brand name be used that has a good track record over a period of at least five years.
7. The sealer material should contain not less than 5 percent solids; over 7 percent is preferable. Solvent-based sealers are strongly recommended as opposed to water-based sealers, because the molecular structure is smaller and the penetration will be better and the application, therefore, will last longer and perform better.
8. Apply the selected sealer candidates to test panels on the building at a suitable location that is reasonably hidden. Allow these test panels to cure and weather for several months. Then inspect them to determine satisfactory performance as to color change, water permeability, etc.
9. The sealer should be applied in two (2) flood coats with a 12-in. rundown, or at the application rate recommended by the sealer manufacturer for the specific substrate.
10. It is suggested that the owner and/or architect require a written warranty from the contractor performing the work and the sealer manufacturer as to precisely what work is being performed and what the results will be over what period of time.
If these cautions are carefully studied and applied to the particular project and found to be applicable, a successful treatment is quite likely. However, failure to consider these items, almost certainly will result in a poor performing application and perhaps in severe harm being done to the masonry wall in question.