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Historic Preservation - Technical Procedures

Spectitle:

Cleaning Masonry Using Ammonium Fluoride Treatment

Procedure code:

0451003R

Source:

Outdoor Sculpture Manual - Center For Public Buildings

Division:

Masonry

Section:

Masonry Cleaning

Last Modified:

02/24/2012

Details:

Cleaning Masonry Using Ammonium Fluoride Treatment



CLEANING MASONRY USING AMMONIUM FLUORIDE TREATMENT


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


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on the removal of dirt
         from masonry by poulticing with an ammonium fluoride
         paste.

    B.   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.

    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).

    D.   For additional information on poulticing, see 04455-02-R.


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.   Ammonium fluoride:

         CAUTION:  USE EXTREME CAUTION WITH THIS MATERIAL.

         1.   Other chemical or common names include Ammonium
              bifluoride; Ammonium hydrogen fluoride.

         2.   Potential Hazards:  TOXIC; CORROSIVE TO FLESH;
              CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS;
              FLAMMABLE.

         3.   Available from chemical supply house or dairy
              supply distributor.

    B.   White absorbent material such as molding plaster,
         untreated white flour, powdered chalk, talc, fullers
         earth, etc.

    C.   Mineral water

2.02 EQUIPMENT

    A.   Glass or ceramic bowl for mixing ingredients

    B.   Wooden utensil for stirring the ingredients

    C.   Wood or plastic spatula

    D.   Brushes - one fine stencil brush, and a natural bristle
         brush


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:  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.   Mix ammonium fluoride with one of the white absorbent
         materials listed in Section 2.02 above to form a thick
         paste.

    B.   Thoroughly wet the surface to be treated with mineral
         water.

    C.   Apply the paste with a fine stencil brush (be sure to
         eliminate any air pockets or voids created in the
         application).

    D.   Let the paste dry for twenty minutes.

    E.   Carefully remove the paste with a wood or plastic
         spatula, or a stiff natural bristle brush.

    F.   Thoroughly rinse the surface with clean, cool mineral
         water and allow to dry.

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

                         END OF SECTION