and methods shall not result in staining, erosion, marring, or other damage
to the surfaces of the structure. Following an initial inspection and
evaluation of the structure and surfaces, the structure shall be given a
surface cleaning. The surface cleaning shall be completed prior to start
of repair work, and sampling and testing of mortars. The cleaning shall
provide for the complete cleaning of all exterior masonry surfaces of the
structures, removing all traces of moss, dirt, and other contaminants. The
cleaning shall provide a clean masonry surface to allow determination of
the masonry's color and shades, finish and texture, and other properties.
Following completion of the surface cleaning of the structure (or side of
structure) the masonry shall be dried prior to the start of any repair
work. The following sequence of methods shall be used to determine the
least aggressive, effective cleaning method:
1.
Water with brushes
2.
Water with mild soap
3.
Water with stronger soap
4.
Water with stronger soap plus ammonia
5.
Water with stronger soap plus vinegar (but not on calcareous masonry)
6.
Stronger chemical cleaners, only when above methods are determined
to
be ineffective by the Contracting Officer
3.2.1
Project Conditions
Masonry surfaces shall be cleaned only when air temperatures are above 5
degrees C 40 degrees F and will remain so until masonry has dried out, but
for not less than 7 days after completion of the work.
3.2.2
Chemical Cleaners
Acidic chemical cleaners shall not be used on limestone, marble, concrete
and other calcareous (calcium containing) masonry materials. If chemical
cleaners are used on such materials, they shall be alkaline based and
utilized with neutralizing afterwashes.
3.2.3
Test Patches
The materials, equipment, and methods to be used in cleaning shall be
demonstrated in a test section approximately 1 by 1 m 3 by 3 ft square.
The location of the test section, and the completed test section shall be
subject to approval. The cleaning process shall be adjusted as required
and the test section rerun until an acceptable process is obtained. Test
patches shall be located in inconspicuous areas of the building. The areas
tested shall exhibit soiling characteristics representative of those larger
areas to be cleaned. Tests shall also be conducted on areas to be stripped
of paint. Tested areas shall be allowed to dry before a determination is
made on the effectiveness of a particular treatment.
3.2.4
Paint Removal
Paint and other coatings shall be removed from masonry surfaces in areas
indicated prior to general cleaning. Masonry shall not be damaged or
marred in the process of paint removal. Areas where paint is to be removed
shall first be cleaned with water and detergent solution to remove surface
dirt, rinsed, and allowed to dry. Chemical paint removers shall be applied
in accordance with manufacturer's instructions. Surrounding painted
surfaces to remain intact shall be protected from exposure to chemical
paint removers to avoid damage. Paint containing lead that is to be
removed shall be removed in accordance with Section 13281A LEAD BASED PAINT
SECTION 04900
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