Removal Of Waterproof Coating From Granite
- Procedure code:
- Federal Building/Courthouse, Sioux Falls, Ia
- Last Modified:
REMOVAL OF WATERPROOF COATING FROM GRANITE
A. This procedure includes guidance on how to remove a
surface applied waterproof coating which has begun to
discolor and flake-off due age, poor penetration or
B. Safety Precautions:
1. Workers shall be provided with protective clothing
including full head and face protection and noise
2. Helmet shall be "air-line" type to maintain
positive air pressure inside helmet to prevent the
ingress of dangerous abrasive dust.
C. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
A. Fine abrasive - type to be determined by field testing
completed prior to actual cleaning. Possible abrasives
include talc, ground nut shells or egg shells, both
angular and smooth sands depending on cutting edge
required to remove deteriorated coating.
B. Water - clean, clear, potable.
A. Air compressor (with pressure gauge)
B. Appropriate nozzle - long venturi nozzle for flat
surfaces with consistent soiling conditions; short
straight nozzles for detailed areas. Shapes to be
determined by field testing. Nozzle should be type that
allows for different modes of operation, abrasive and
air, abrasive and water, air only and water only to allow
greater control by operator.
C. High pressure water lance (maximum pressure not to exceed
3.01 ERECTION, INSTALLATION, APPLICATION
A. Using low pressures (60 to 80 psi at the compressor),
apply stream of abrasive/water mixture to wall surface
being cleaned. Begin with lowest pressure and softest
abrasive determined appropriate by pretesting.
1. Maintain minimum 12" from the surface of the stone
and do not allow stream to stay in one spot for
more than a few seconds.
2. Do not allow direct blasts at mortar joints.
3. Check work frequently and stop cleaning as soon as
coating has been removed.
4. Reduce air pressure if damage to stone occurs.
5. To avoid "gun-shading" do not rush through work,
and maintain steady, even control.
B. After surfaces have been cleaned, wash surfaces to remove
all traces of slurry and spent abrasives. Use a low-volume,
high-pressure water lance, with pressure not to
exceed 400 psi at the compressor. Use hand-sprays as
necessary on small scale details.
END OF SECTION