General Cleaning Of Exterior Polished And Honed Granite

CSI Division:
Division 4- Masonry
Last Modified:

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Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.

We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.




A. This procedure includes guidance on cleaning exterior
polished and honed granite.

B. Safety Precautions:

1. The work specified herein requires knowledge of
older materials and methods and a high degree of
skill to execute properly. This work should be
performed only by an experienced, pre-qualified
contractor. It is not recommended that building
maintenance personnel perform this work.

2. This outline specification contains recommended
materials which may be toxic. The manufacturer s
literature on application techniques, appropriate
protection for workers and disposal procedures for
materials should be complied with in conjunction
with all regulatory requirements referenced in this
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

3. Submittals

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. Product Data:

1. Submit manufacturer's technical data for each
product indicated including recommendations for
their application and use to the Contracting
Officer or the designated representative. Include
test reports and certifications substantiating that
products comply with requirements.

2. Prior to commencing the cleaning operations, submit
to the Contracting Officer or the designated
representative a written description of the
materials, methods, and equipment proposed for
cleaning each type of masonry included in the work
of this section including, but not limited to:
cleaning products and chemical components, method
of application, dilution of application,
temperature of application, length of time of
surface contact, method of rinsing surface
(temperature, pressure, and duration), repetition
of procedures, etc.

3. Protection Program: Prior to commencing the
cleaning operations, the Contractor shall submit to
the Contracting Officer or the designated
representative for approval, a written description
of proposed materials and methods of protection for
preventing damage to adjacent materials, vehicular
and pedestrian traffic, and the building interior
during the cleaning of stone.

B. Samples:

1. Prior to the start of masonry cleaning, prepare for
approval a sample panel, approximately 3 x 3 feetin
area, on each type of masonry included in the work
where directed by the Contracting Officer or the
designated representative.

2. Adjust the chemical concentrations, working
pressures and methodologies during test panel
cleaning, as directed by the Contracting Officer s

3. Clean sample panels using methods, materials, and
working pressures previously submitted and
approved. Perform sample panel cleaning in the
presence of the Contracting Officer or the
designated representative.

4. Where chemical cleaners and poultices are tested,
perform testing in the presence of the
manufacturer's representative.

5. Obtain written approval from the Contracting
Officer or the designated representative of
cleaning methods, working pressures, materials,
equipment used and sample panels before proceeding
with building cleaning operations. Allow a minimum
of seven calendar days after completion of sample
cleaning to permit study of sample panels for
negative reactions. Retain approved panels in
unaltered condition, suitably designated during
construction as a standard for judging completed


A. Qualifications:

1. The objective of stone cleaning is to remove
soiling, stains and crusts from the granite without
damaging underlying material and to give all stone
a clean, uniform appearance without blotches,
streaks, or other irregularities. Use the gentlest
means to meet the cleaning objective.

2. Cleaning Standard: Prepare sample panels for
approval which shall establish a standard for
general stone and brick cleaning. Cleaning shall
not commence until written approval is obtained for
sample panels and submittals from the Contracting
Officer or the designated representative.

B. Regulatory Requirements: Comply with municipal and
Federal regulations governing the cleaning, chemical
waste disposal, scaffolding protection to adjacent
properties and workers.


A. Environmental Requirements:

1. No cleaning shall be executed when air or masonry
surface temperature is below 45 degrees F, unless adequate,
approved means are provided for maintaining a 45 degrees F,
temperature of the air and materials during, and
for 48 hours subsequent to, cleaning.

2. Perform cleaning and rinsing of the exterior
masonry only during daylight hours.



A. ProSoCo, Inc.

B. Chemique, Inc.

C. Diedrich Technologies, Inc.


A. Detergent: Commercially available surface active liquid
cleansing agent specifically formulated for cleaning
masonry, such as "Ion 417" (Chemique Inc.), or
approved equal.

B. Liquid Strippable Masking Agent: Manufacturer's standard
liquid, film forming, strippable masking material for
protecting glass, metal and polished stone surfaces from
damaging effect of acidic and alkaline masonry cleaners,
such as "Sure Klean Strippable Masking" (ProSoCo, Inc.), "Diedrich
Acid Guard" (Diedrich Technologies, Inc.), or approved

C. Water: Potable, non-staining and free of oils, acids,
alkalis and organic matter .


A. Brushes: Natural fiber bristle only. The use of wire
brushes or steel wool is not permitted.

B. Garden hose with fan tip nozzles



A. Protection:

1. Take all necessary precautions and measures to
protect surrounding materials on the site, surfaces
of the building not being cleaned, adjacent
buildings, pedestrians and vehicles from coming in
contact with cleaning chemicals, over spray, or
runoff. Products used for masonry cleaning may be
harmful to painted, polished, glazed, or metallic
surfaces. Any damage to materials caused by the
cleaning operations is unacceptable and shall be
repaired or replaced by the Contractor to the
satisfaction of the Contracting Officer or the
designated representative at no cost to the

2. Provide protection from water damage to building,
structure, or building contents as required.

3. Protect trees and plants around the building from
contamination or damage. The Contractor shall be
responsible for replacing with new stock, any
trees, shrubbery or grass damaged by the cleaning

4. Test all drains and other water removal systems to
assure that drains and systems are functioning
properly prior to performing any cleaning
operations. Notify Contracting Officer or the
designated representative immediately of any and
all drains or systems that are found to be stopped
or blocked. Contractor shall repair drains if so
directed by the Contracting Officer or the
designated representative. Do not begin work of
this Section until the drains are in working order.

5. Provide a method to prevent solids such as stone or
mortar residue from entering the drains or drain
lines. Contractor shall be responsible for cleaning
out drains and drain lines that become blocked or
filled by sand or other solids because of work
performed under this Contract.


A. Dilute detergent with 3 parts water to 1 part
concentrate, or use appropriate dilution as determined by
field testing.

B. Brush apply to granite, scrub for 10 minutes with stiff
bristle brushes.

C. Rinse the treated area thoroughly using pressurized cold
water, not exceeding 300 psi, sprayed through nozzles
fitted with 15 to 20" wide tips. Nozzles shall be held
perpendicular to the surface at a working distance of 1.4
to 2.0 feet. All pressure pumps shall be equipped with
working pressure gauges.
D. Rinse from the bottom of the treated area to the top
flushing each section of the surface with a concentrated
stream of water. To avoid streaking on vertical walls,
take care to keep the wall below wet and rinsed free of
cleaner and residues.

E. The surfaces below the sections of brick to be cleaned
shall be protected from run-off.

F. Repeat procedures if necessary to remove heavier build-up
of soiling.

Last Reviewed: 2017-08-13