Cleaning Unpolished White Granite

Procedure code:
National Capitol Region Specifications
Last Modified:




    A.   This procedure includes guidance on cleaning unpolished Sierra white
         and Milford pink granite.  This treatment shall not be used on any polished granite.
    B.   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).  

    C.   Materials conservator should review specifications to
         ensure they are appropriate.


    A.   Pressure Readings:  Described herein, shall be measured
         at the nozzle of the spray apparatus, not at the masonry
         surfaces as follows:

         1.   Low pressure wash shall measure between 100 psi and
              400 psi.

         2.   Medium pressure wash shall measure between 400 psi
              and 800 psi.

         3.   High pressure wash shall measure between 800 psi
              and 1200 psi.

    B.   Construction Engineer:  As referred to hereinafter, means
         that person or persons representing the Government or
         acting for the Governments Contracting Officer.


    A.   Cleaning operations shall be carried out by a firm with
         a minimum of five years specialized experience in the
         cleaning of historic architectural masonry.

    B.   The Contractor shall submit to the Architect written
         record of projects for which the Contractor has performed
         masonry cleaning of materials the same as those on this

    C.   The Contractor shall arrange with the Construction
         Engineer for a site test of protective methods and
         cleaning materials and methods which he proposed to use
         to prove that chemical damage to glass, polished stone,
         or air conditioning units, painted surfaces,
         trees, shrubbery, and grass will not occur.

    D.   The Contractor shall test all drains which he plans to
         use to assure that those drains are functioning properly
         before beginning masonry cleaning operation in each area.
         The Contractor shall immediately report the location of
         drains which are stopped up or blocked to the
         Construction Engineer.

    E.   During cleaning operations, the Contractor shall prevent
         solids, such as masonry cleaning residue, from the drains
         and drain lines.  Drains shall be serviced daily.  The
         Contractor will be held responsible for cleaning out
         drains and drain lines which become blocked or filled as
         a result of work performed under this contract.

    F.   Regulatory Requirements:  Comply with municipal and
         Federal regulation governing the cleaning, chemical waste
         disposal, scaffolding and protection to adjacent

    G.   Field Samples:

         1.   The Contractor shall clean 25 square feet
              (approximate) sample panels on each type of
              masonry.  Locations of sample panels to be cleaned
              will be selected by the Construction Engineer.

         2.   Prior to cleaning sample panels, the Contractor
              shall submit to the Construction Engineer in
              his written description of cleaning methods,
              working pressures, materials and equipment
              proposed for use in cleaning each type of masonry.
              Actual samples of any chemicals shall be submitted
              along with letters of certification from
              manufacturer that chemical concentrations do not
              exceed those specified above.

         3.   Adjust the chemical concentrations, working
              pressures and methodologies during test panel
              cleaning, as directed by the Construction Engineer.

         4.   Sample panels shall be cleaned by the Contractor
              using methods, materials, and working pressures
              previously submitted and approved.  Sample panel
              cleaning shall be performed in the presence of the
              Construction Engineer.  The working pressures
              during sample panel cleaning shall be varied up to
              the previously submitted and approved capacities to
              determine the best working pressure.

         5.   The Contractor shall obtain the Construction
              Engineers written approval of cleaning methods,
              working pressures, materials, equipment used and
              sample panels before proceeding with building
              cleaning operations.  For this written approval
              purpose, the Contractor shall allow a minimum of
              seven calendar days after completion of sample
              cleaning to permit the Construction Engineer to
              study the sample panels for negative reactions.
              Approved sample panels shall be marked and left
              unaltered.  Approved samples will be used as the
              standard for similar work throughout the project.


    A.   Packing and Shipping:  Deliver materials to the site in
         the manufacturer's original and unopened containers and
         packaging, bearing labels as to the type of material,
         brand name and manufacturer's name.  Delivered materials
         shall be identical to tested materials.

    B.   Storage and Protection:  Store materials off the ground
         in a dry, clean location.  Remove materials which are
         damaged or otherwise not suitable for use from the job


    A.   Environmental Requirements:  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
         for 48 hours subsequent to cleaning.


    A.   Perform general cleaning of masonry before the repair and
         pointing of the masonry, unless mortar joints are in poor
         condition.  Serious deterioration could foster excessive
         moisture infiltration into the masonry.  Perform final
         wash down of the masonry no less than 30 days after
         masonry repair and pointing is completed.

    B.   Perform cleaning and washing of the exterior masonry only
         during hours of natural daylight.



    A.  ProSoCo, Inc.
    B.  Diedrich Technologies, Inc.


    A.   White Granite Cleaner:  Solution of 4% hydrofluoric acid
         with a trace of phosphoric acid (less than 0.1%), such as
         Sure Klean Restoration Cleaner (ProSoCo, Inc.),
         "Diedrich 101 Masonry Restorer Super Concentrate" - diluted 1:4 to achieve
         a 4% maximum acid solution (Diedrich Technologies, Inc.),
         or approved equal.

    B.   Warm Water:  Potable, non-staining and free of oil,
         acids, alkalis, and organic matter, heated to
         approximately 180 degrees F.


    A.   High Pressure Water Equipment: USE CAUTION.  Provide
         equipment capable of providing water pressure, as
         measured at the pump, in the range 25 psi up to 800 psi,
         at a temperature of 160 degrees to 180 degrees F. and at
         a constant water flow of 4-6 gallons per minute.
         Equipment shall have intact, accurate calibrated,
         operating gauges to monitor water pressure.  See 04510-
         04-S and 04510-05-S for usage guidelines and dangers in
         using high-pressure cleaning equipment.

    B.   Spray tips: Fan type, stainless steel, dispersing a 25-50
         degree fan spray and a cone shaped spray tip.

    C.   Brushes: Nylon or Fiber bristle brushes.

    D.   Protective clothing: Chemicals can cause severe burning
         of skin, eyes and lungs.  Provide protective clothing
         appropriate to the materials and equipment in use.



    A.   Tests/Inspection:  Inspect site conditions and drainage
         to determine that cleaning operations can be conducted
         without endangering or causing interference with other
         materials or work at the site and to determine that
         drainage is adequate to safely carry away all waste
         material produced during the cleaning operations.


    A.   Protection:  

         1.   All necessary precautions shall be taken to protect
              all parts of the building not being cleaned from
              damage during the cleaning process.  The Contractor
              shall use masking tape where applicable to seal
              edges of coverings during masonry cleaning
              operations, and remove such coverings when masonry
              cleaning operations are completed on that section
              of the building.

         2.   All work shall proceed in an orderly fashion;
              working from top to bottom of each scaffold width
              and from one end of the elevation to the other.  

         3.   Take all necessary precautions and protective
              measures to protect surrounding materials on the
              site and surfaces of the building not being
              cleaned, from coming in contact with the cleaning
              materials and run-off.

         4.   Fully protect all metals, painted surfaces,
              limestone and polished black granite from coming in
              contact with acid cleaner.

         5.   Take necessary precautions to protect workmen and
              pedestrians from cleaning chemicals, overspray and

         6.   Provide protection to prohibit chemicals or run-off
              from coming in contact with any painted, polished
              or metallic surfaces.  Build dams to divert flowing
              water to drains in compliance with municipal codes.
              Contain or dilute used cleaning materials prior to
              disposal in accordance with code.

    A.   Pre-wet the granite with a low pressure (100-400 psi)
         warm water wash.

    B.   Apply cleaner undiluted to maintain 4% maximum solution
         evenly by spraying at 125 psi or with soft fiber bristled
         brush.  Let solution stand for 3-5 minutes.

    C.   Rinse granite with clean water at medium pressure (400-
         800 psi), removing all cleaner from stone.

    D.   Reapply cleaner undiluted to maintain 4% maximum solution
         and let stand 3-5 minutes.

    E.   Rinse granite with clean water at medium pressure (400-
         800 psi) to remove all acid wash and soil from stone.

    F.   Stone shall be evenly clean without streaking or

    G.   Apply cleaner at no more than 4% hydrofluoric acid and
         nor more than two times.

                         END OF SECTION

Last Reviewed 2014-12-23