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Historic Preservation - Technical Procedures

Spectitle:

Spot Cleaning Iron Stains On Granite

Procedure code:

0446501R

Source:

Us Custom House/P.O., St. Louis, Mo - Gsa/Pbs

Division:

Masonry

Section:

Granite

Last Modified:

02/24/2012

Details:

Spot Cleaning Iron Stains On Granite



SPOT CLEANING IRON STAINS ON GRANITE


THE CLEANING OR REMOVAL OF STAINS FROM STONE MAY INVOLVE THE USE
OF LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON ADJACENT
MATERIAL, DISCOLOR THE STONE OR DRIVE THE STAINS DEEPER INTO THE
POROUS STONE.  USE THE PRODUCTS AND TECHNIQUES DESCRIBED HERE ONLY
FOR THE COMBINATIONS OF DIRT/STAIN AND STONE SPECIFIED.


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on removing iron stains
         from granite surfaces by scrubbing with a chemical
         cleaner or detergent, or by poulticing with a chemical
         solvent.

    B.   For guidance on spot cleaning other stains on granite,
         refer to the following:

         1.   For copper/bronze stains:  See 04465-02-R.

         2.   For oil stains:  See 04465-03-R.

    C.   Safety Precautions:

         1.   DO NOT save unused portions of stain-removal
              materials.

         2.   DO NOT store any chemicals in unmarked containers.

         3.   EXCELLENT VENTILATION MUST BE PROVIDED WHEREVER ANY
              SOLVENT IS USED.  USE RESPIRATORS WITH SOLVENT
              FILTERS.

         4.   No use of organic solvents indoors should be
              allowed without substantial air movement.  Use only
              spark-proof fans near operations involving
              flammable liquids.

         5.   Provide adequate clothing and protective gear where
              the chemicals are indicated to be dangerous.

         6.   Have available antidote and accident treatment
              chemicals where noted.

    D.   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).

    E.   For general information on the characteristics, uses and
         problems associated with granite, see 04465-01-S.


PART 2---PRODUCTS

2.01 MATERIALS

    NOTE:  Chemical products are sometimes sold under a common
    name.  This usually means that the substance is not as pure as
    the same chemical sold under its chemical name.  The grade of
    purity of common name substances, however, is usually adequate
    for stain removal work, and these products should be purchased
    when available, as they tend to be less expensive.  Common
    names are indicated below by an asterisk (*).

    A.   For Scrubbing by Hand:

         1.   Chemical Cleaning Compound:  Hydrofluoric (HF) and
              phosphoric (H3PO4) acids in concentrations not
              exceeding 5% weight to volume, with surfactants
              such as ethoxylated alkylphenols and ethoxylated
              alcohols at concentration of 1 to 2% weight to
              volume.

         -OR-

         2.   Cleaning Detergent:  Cleaning detergent designed
              for use on masonry surfaces, free of deleterious
              amounts of acids, alkalies and organic materials,
              as recommended by manufacturer for masonry surfaces
              of work to be cleaned as acceptable.

    B.   For Poulticing:

         1.   Sodium Citrate (appears like enlarged salt
              granules):

              a.   Other chemical or common names include Citrate
                   of soda*.

              b.   Available from chemical supply house,
                   drugstore or pharmaceutical supply
                   distributor.

         2.   Glycerol (C3H8O3):

              a.   A sweet syrupy hygroscopic trihydroxy alcohol
                   usually obtained by the saponification of fats
                   and used especially as a solvent and
                   plasticizer.

              b.   Other chemical or common names include
                   Glycerine; Glyceryl hydroxide; Glycyl alcohol;
                   1,2,3-propanetriol; Propenyl alcohol.

              c.   Potential Hazards:  FLAMMABLE.

              d.   Available from chemical supply house, drug
                   store or hardware store.

         -OR-

         3.   Proprietary preparations of paste are also
              available and should be used according to their
              manufacturer's published instructions.

    C.   Clean, potable water

2.02 EQUIPMENT

    A.   For Poulticing:

         1.   Glass or ceramic container for mixing the solution

         2.   Wooden utensil for stirring the ingredients

    B.   Wood or plastic spatula

    C.   Stiff bristle brush (non-metallic)


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:

         1.   The use of wire brushes, steel wool, or abrasive
              tools for cleaning will not be permitted.

         2.   Provide adequate wash solutions (i.e. water, soap
              and towels) before starting the job.

3.02 ERECTION, INSTALLATION, APPLICATION

    NOTE:  DO NOT TRY MORE THAN ONE TREATMENT ON A GIVEN AREA
    UNLESS THE CHEMICALS USED FROM PRIOR TREATMENT HAVE BEEN
    WASHED AWAY.

    A.   Scrubbing Iron Stains (for larger areas):

         1.   Apply chemical cleaner or detergent to stained
              surface following manufacturer's instructions.

         2.   Scrub the surface by hand using a stiff (non-metallic)
              bristle brush.  Begin at the top of the stained area
              and work down.

         3.   Thoroughly rinse the surface with clean, clear
              water and allow to dry.

         4.   Repeat as necessary to achieve the desired level of
              cleanliness.

    B.   Poulticing Iron Stains (for small localized areas):

         1.   Mix one part sodium citrate in six parts water, and
              mix with 7 parts glycerine to form a thick paste.

         2.   Thoroughly wet the concrete surface to be treated
              with clean, clear water.

         3.   Apply the mixture to the stained area using a wood
              or plastic spatula and allow to dry.  Be sure to
              spread the poultice well beyond the stained area.
              The liquid portion of the paste will migrate into
              the concrete where it will dissolve some of the
              staining material.  Then the liquid will gradually
              move back beyond the concrete surface and into the
              poultice, where it will evaporate, leaving the
              dissolved staining material in the poultice.

         4.   When the poultice has dried, brush or scrape it off
              with a wooden scraper.  

         5.   Thoroughly rinse the area with clean, clear water
              while scrubbing with a stiff bristle brush and
              allow to dry.

         6.   Repeat the process as necessary to achieve the
              desired level of cleanliness.

    NOTE:  Finished work shall show no signs of stains, scratches,
    streaks or runs of discoloration, mortar damage or other like
    defects from use of cleaners.  Leave all masonry surfaces neat
    and clean.

                         END OF SECTION