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Historic Preservation - Technical Procedures

Spectitle:
Removing Dirt From Brick Masonry

Procedure code:
0421109R

Source:
Tech Notes On Brick Construction - 20

Division:
Masonry

Section:
Brick Unit Masonry

Last Modified:
02/24/2012

Details:
Removing Dirt From Brick Masonry



REMOVING DIRT FROM BRICK MASONRY


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 THE 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 cleaning brick
         masonry to remove accumulations of surface dirt.  

    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).


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   Diedrich Chemicals Restoration Technologies, Inc.
         7373 S. 6th Street
         Oak Creek, Wisconsin  53154
         414/764-0058 or 800/323-3565

    B.   ProSoCo Inc.
         755 Minnesota Avenue
         P.O. Box 1578
         Kansas City, KS  66117
         913/281-2700

    C.   Red Devil, Inc.
         2400 Vauxhall Road
         Union, NJ  07083
         201/688-6900 or 800/423-3845

2.02 MATERIALS

    A.   For Light Dirt:

         1.   Trisodium Phosphate:

              NOTE:  THIS CHEMICAL IS BANNED IN SOME STATES SUCH
              AS CALIFORNIA.  REGULATORY INFORMATION AS WELL AS
              ALTERNATIVE OR EQUIVALENT CHEMICALS MAY BE
              REQUESTED FROM THE ENVIRONMENTAL PROTECTION AGENCY
              (EPA) REGIONAL OFFICE AND/OR THE STATE OFFICE OF
              ENVIRONMENTAL QUALITY.

              a.   Strong base-type powdered cleaning material
                   sold under brand names.

              b.   Other chemical or common names include Sodium
                   Orthophosphate; Tribasic sodium phosphate;
                   Trisodium orthophosphate; TSP*; Phosphate of
                   soda*; (also sold under brand names such as
                   Red Devil).

              c.   Potential Hazards:  CORROSIVE TO FLESH.

              d.   Available from chemical supply house, grocery
                   store or supermarket or hardware store.

         2.   Laundry detergent

    B.   For Heavy Dirt:

         1.   Muriatic acid (generally available in 18 degree and
              20 degree Baume solutions):

              CAUTION:  DO NOT USE MURIATIC ACID ON LIGHT COLORED
              BRICK AS THEY ARE MORE SUSCEPTIBLE TO "ACID BURN"
              THAN DARKER BRICKS.

              a.   A strong corrosive irritating acid.

              b.   Other chemical or common names include
                   Chlorhydric acid; Hydrochloric Acid (30-35%):
                   Hydrogen chloride; Marine acid*; Spirit of
                   salt*; Spirit of sea salt*.

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

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

         -OR-

         Commercial Cleaning Compound such as "Sure Klean
         Restoration Cleaner" (ProSoCo, Inc.), or approved equal.

    C.   For Rough-textured Brick:

         1.   Oxalic acid (COOH)2 or (H2C2O4):

              a.   A poisonous strong acid that occurs in various
                   plants as oxalates and is used especially as a
                   bleaching or cleaning agent and in making
                   dyes.

              b.   Other chemical or common names include
                   Ethanedioic acid.

              c.   Potential Hazards:  TOXIC; CORROSIVE TO
                   CONCRETE, STEEL, WOOD OR GLASS.

              d.   Available from chemical supply house, dry
                   cleaning supply distributor, drugstore or
                   pharmaceutical supply distributor, hardware
                   store, or photographic supply distributor (not
                   camera shop).  (Often sold under a
                   manufacturer's brand name; the chemical name
                   may appear on the label.)

    D.   White vinegar or commercial neutralizer such as "Sure
         Klean Masonry Restorer" (ProSoCo, Inc.), 101 Masonry
         Restorer/Cleaner (Diedrich Chemicals), or approved equal.

    E.   Clean, potable water

2.02 EQUIPMENT

    A.   Non-metallic container

    B.   Stiff bristle brush

    C.   Wooden or other non-metallic scraper


PART 3---EXECUTION

3.01 ERECTION, INSTALLATION, APPLICATION

    NOTE:  WHEN CLEANING, AVOID OVERCLEANING.  AIM FOR ACHIEVING
    85% CLEAN.  MOST DAMAGE OCCURS WHEN ATTEMPTING TO CLEAN THE
    LAST 15%.  

    NOTE:  BEGIN CLEANING BY USING THE GENTLEST METHOD POSSIBLE.
    TEST CLEAN A SMALL AREA BEFORE ATTEMPTING TO CLEAN LARGE
    AREAS.

    A.   Mix solution or cleaner:

         1.   For light dirt:  Mix 1/2 cup (0.14 L) trisodium
              phosphate and 1/2 cup (0.14 L) laundry detergent in
              1 gallon (3.79 L) clean, clear water.

         2.   For heavy dirt:  Mix 9 parts clean water with 1
              part muriatic acid in a non-metallic container.
              POUR ACID INTO WATER NOT THE REVERSE.

              CAUTION:  DO NOT ALLOW METAL TOOLS TO COME IN
              CONTACT WITH THE ACID.  DO NOT MIX THE ACID
              SOLUTION STRONGER THAN RECOMMENDED AS A STRONGER
              CONCENTRATION MAY STAIN THE MASONRY SURFACE.

              -OR-

              Try using a commercial cleaning compound suitable
              for use on brick (follow manufacturer's recommended
              dilution and application instructions).

         3.   For rough-textured brick:  Mix 1 lb (0.45 kg)
              oxalic acid crystals with 1 gallon (3.79 L) of
              water.

    B.   Apply the solution to the brick and scrub the surface
         using a stiff bristle brush.  Allow the solution to
         remain on the brick for 5 to 10 minutes or as recommended
         by manufacturer (if proprietary product is used).

    C.   Use a wooden scraper to remove heavy crusts as necessary.
         DO NOT USE METAL SCRAPERS OR CHISELS AS METAL MARKS LEFT
         ON THE BRICK WILL OXIDIZE AND CAUSE STAINING.

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


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

    F.   If acid or commercial cleaner is used, neutralize the
         surface using white vinegar or a proprietary chemical
         neutralizer.  A neutral pH (7 pH) should be achieved.

         1.   Allow neutralizer to stand on wall about three
              minutes before rinsing.  DO NOT LET IT DRY!

         2.   Thoroughly rinse the surface with clean, clear
              water.

         3.   Test the pH with litmus paper or phenolphthalein:

              a.   Dissolve a 2" piece of phenolphthalein in
                   denatured alcohol.  

              b.   Brush the solution onto the surface.  If it
                   turns a shade from pink to magenta there is
                   still chemical residue.  

         4.   Continue to neutralize the surface and test until
              there is no color change in the phenolphthalein
              solution or the litmus paper registers neutral.

                             END OF SECTION