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Historic Preservation - Technical Procedures

Spectitle:

Removing Salts From Granite

Procedure code:

0446516R

Source:

National Capitol Region Specifications

Division:

Masonry

Section:

Granite

Last Modified:

02/24/2012

Details:

Removing Salts From Granite



REMOVING SALTS FROM GRANITE


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on the removal of
         surface dirt on all areas granite, and rinsing of ice-
         melting salts that have caused surface-erosion of the
         stone.

    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).

1.02 QUALITY ASSURANCE

    A.   Qualifications:  

         1.   Contractor performing the work shall have a minimum
              of 5 years experience in masonry restoration work
              of the type described for this project.

         2.   If requested by the Owner, furnish a statement of
              the experience and qualifications of the firm and
              of the key personnel who will work on this project.
              Include the names and addresses of successful
              projects completed, and for each, the name and
              address of the owner and the architect.

    B.   Reference Standards:

         1.   Secretary of the Interior's "Standards for
              Rehabilitation".

         2.   Preservation Brief No. 1, "The Cleaning and
              Waterproofing of Historic Masonry Buildings".

    C.   Test Panels:  Each alternative method for each type of
         cleaning.


PART 2---PRODUCTS

2.01 MATERIALS

    A.   Clean, potable water

2.02 EQUIPMENT

    A.   Pressure water rinsing equipment (measuring between 100
         and 400 psi for low-pressure; between 400 and 800 psi for
         medium pressure).

    B.   Fan-type spray tips (25 degree fan spray)

    C.   Stiff fiber-bristle brushes


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:

         1.   This work should be tested in conjunction with
              water soaking of other stone surfaces.

         2.   Joints should be tight to ensure protection of
              interior wall finishes.

3.02 ERECTION, INSTALLATION, APPLICATION

    A.   General rinsing of granite surface:  Maximum 800 PSI, 5-
         10 GPM, 25  fan angle, not less than 6" from surface, at
         an angle of 45  to 90  from wall surface.

    B.   Salt Removal:  

         1.   Use water soaking method employing finely misted
              sprays from full flow nozzles, 10-50 PSI per
              nozzle.

         2.   Soak for four hour period followed by 500 PSI
              pressure rinse.

                         END OF SECTION