HAZARD ABATEMENT, TARGET HOUSING & CHILD OCCUPIED FACILITIES.
3.2.5
Water Cleaning
3.2.5.1
Pressure Spraying
Water shall be spray applied to masonry surfaces to comply with
requirements indicated by test patches for location, purpose, water
temperature, pressure, volume, and equipment. Unless otherwise indicated,
the surface washing shall be done with clean, low pressure water (pressure
of less than 0.38 Mpa 55 psi and 9.5 to 11.4 Lpm 2.5 to 3 gpm discharge)
and the spray nozzle shall not be held less than 300 mm 12 inches from
surface of masonry. Water shall be applied side to side in overlapping
bands to produce uniform coverage.
3.2.5.2
Handscrubbing
Pre-wetted surfaces shall be scrubbed using hand-held natural bristle or
nylon brushes. Wire brushes shall not be used. Surfaces to be cleaned
shall be scrubbed to remove surface contaminants.
3.2.5.3
Rinsing
Scrubbed surfaces shall be rinsed clean of all contaminants and cleaning
solutions with water in a low-to-moderate pressure spray, working upwards
from bottom to top of each treated area. The rinsing cycle shall remove
all traces of contaminants and cleaning solutions.
3.2.6
Chemical Cleaning
Chemical cleaning of historic masonry shall use the gentlest means possible
to achieve the desired result as determined by test patches. Chemical
cleaning shall be the use of any product in addition to water, including
detergents, ammonia, vinegar, and bleach. Cleaning shall proceed in an
orderly manner, working from top to bottom of each scaffold width and from
one end of each elevation to the other. Cleaning shall result in uniform
coverage of all surfaces, including corners, moldings, interstices and
shall produce an even effect without streaking or damage to masonry.
Chemical cleaners shall not be applied to the same masonry surfaces more
than twice.
3.2.6.1
Surface Prewetting
Masonry surfaces to be cleaned with chemical cleaners shall be wetted with
water using a low pressure spray before application of any cleaner.
3.2.6.2
Acidic Chemical Cleaning
Acidic chemical cleaners shall be applied according to manufacturer's
instructions. Acidic chemical cleaners shall not be applied to masonry
with high calcium content (e.g. marble, limestone). Acidic cleaners shall
be applied to masonry surfaces by low pressure spray 0.35 Mpa 50 psi max.,
roller, or brush. Cleaner shall remain on masonry surface for the time
period recommended by manufacturer. Manual scrubbing by brushes shall be
employed as indicated by test patches for the specific location. Cleaned
surfaces shall be rinsed with a low-to-moderate pressure spray of water to
remove all traces of chemical cleaner.
SECTION 04900
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