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Historic Preservation - Technical Procedures

Spectitle:

Removing Efflorescence From Ceramic Tile

Procedure code:

0931011R

Source:

Hspg Prepared For Nps - Sero

Division:

Finishes

Section:

Ceramic Tile

Last Modified:

02/24/2012

Details:

Removing Efflorescence From Ceramic Tile



REMOVING EFFLORESCENCE FROM CERAMIC TILE


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


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on removing
         efflorescence from ceramic tile using a hydrochloric acid
         solution.  

         CAUTION:  DO NOT USE THIS TREATMENT ON GLAZED TILE.

    B.   Efflorescence is a condition where white (salt) deposits
         form on the surface of the tile.  The formation of salts
         is usually a sign of excessive amounts of moisture in the
         tile.  Salt deposits on the tile surface may develop
         from:

         1.   Soluble compounds within the tile or in the soil.  

              a.   In the presence of water, these compounds
                   gradually migrate to the wall surface, where
                   they remain when the water evaporates.

              b.   These types of surface deposits are water
                   soluble and can usually be removed by washing
                   the surface with water from a garden hose
                   supplemented by scrubbing with a stiff bristle
                   brush.

         2.   Improper or insufficient rinsing of tile after
              chemical cleaning or repointing.

         3.   The penetration of rain into the tile through
              deteriorated mortar joints.

         4.   Exposure to air pollution, which can result in the
              formation of thick sulfate (salt) crusts on the
              underside of moldings and eaves, areas not
              regularly washed by rainfall.

         5.   Capillary movement of moisture through tile, the
              drying out of walls associated with a damp proofing
              treatment or the elimination of a ground water
              source may increase the amount of salt at or near
              the wall surface.

    C.   These deposits are generally not harmful to the building,
         just unattractive.  However, they should be washed from
         the surface as soon as possible.  Some salt deposits are
         water-soluble for only a brief period after reaching the
         atmosphere.  Carbon dioxide in the atmosphere eventually
         converts these salts into water-insoluble carbonates,
         which are impossible to remove without the use of acids.

    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).


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.   Hydrochloric Acid (30-35%):

         1.   A strong corrosive irritating acid.

         2.   Other chemical or common names include Chlorhydric
              acid; Hydrogen chloride; Muriatic acid* (generally
              available in 18 degree and 20 degree Baume
              solutions); Marine acid*; Spirit of salt*; Spirit
              of sea salt*.

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

         4.   Available from chemical supply house, drugstore or
              pharmaceutical supply distributor, or hardware
              store.

    B.   Clean, potable water

    C.   Clean natural fiber rags


2.03 EQUIPMENT

    A.   Garden hose and pneumatic spray nozzle

    B.   Stiff bristle brushes (non-metallic)


PART 3---EXECUTION

3.01 EXAMINATION

    A.   Before proceeding with steps to remove efflorescence,
         first decide the cause and extent of the problem and make
         repairs as required:

         1.   Determine the age of the structure:  Efflorescence
              on older buildings is typically caused by the
              presence of soluble salts in the construction
              combined with moisture.

         2.   Determine the location of the efflorescence:
              Examination may show where the water is entering.

              a.   Are the salt crystals accumulating on the
                   joints or on the units?

              b.   Can any changes in the wall composition or in
                   the adjacent surroundings be recognized that
                   might show the source of the problem?

         3.   Examine the condition of the tile:  

              a.   CAREFULLY EXAMINE the wall for open gaps or
                   cracks in joints and around openings that
                   could allow water to enter the building.  

                   1)   Are joints properly caulked or sealed?  

                   2)   Are flashings and drips in good
                        condition?


                   3)   Are there open or eroded mortar joints in
                        copings or in sills?

              b.   Carefully note the condition and profile of
                   the mortar joints.

              c.   Repair cracks in tile and/or repoint as
                   necessary before proceeding with the cleaning
                   operations.

         4.   Examine wall sections and details of construction:
              Carefully examine roof and wall junctures and
              flashing details for possible sources of moisture
              entry.

         5.   Examine laboratory test reports on the materials:
              The problem may stem from the composition or misuse
              of the material.

3.02 PREPARATION

    A.   Protection:

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

         2.   Whenever acid is used, the surface should be
              thoroughly rinsed with water as soon as its action
              has been adequate.  Otherwise it may continue
              etching the tile even though the stain is gone.

3.03 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.

    CAUTION:  DO NOT USE THIS TREATMENT ON GLAZED TILE.

    A.   Mix 5% hydrochloric acid in water.

    B.   Using stiff, natural bristle brushes, scrub the affected
         area with the acid solution.

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

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

                             END OF SECTION