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Historic Preservation - Technical Procedures

Spectitle:

Sealing Or Painting Previously Sand-Blasted Brick Masonry

Procedure code:

0421101P

Source:

Developed For Hspg (Nps - Sero)

Division:

Masonry

Section:

Brick Unit Masonry

Last Modified:

02/24/2012

Details:

Sealing Or Painting Previously Sand-Blasted Brick Masonry



SEALING OR PAINTING PREVIOUSLY SAND-BLASTED BRICK MASONRY


THIS PROCEDURE DESCRIBES A REMEDIAL TREATMENT FOR DETERIORATED
BRICK THAT SHOULD ONLY BE USED AS A "LAST RESORT".  SAND-BLASTED
BRICK MASONRY SHOULD BE INSPECTED REGULARLY (ON AN ANNUAL BASIS)
FOR SIGNS OF DETERIORATION.  IF PROBLEMS PERSIST DESPITE MEASURES
TO CONTROL DETERIORATION, THE APPLICATION OF A SEALER OR PAINT MAY
BE APPROPRIATE IN ORDER TO ARREST FURTHER DETERIORATION.  BEFORE
PROCEEDING, SEE 04211-09-S FOR GUIDANCE ON EVALUATING THE CONDITION
OF THE BRICK MASONRY AND MORTAR.


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on sealing sand-blasted
         brick masonry to prevent excessive water penetration into
         the units.  It contains guidance on applying a siloxane
         water repellent coating or latex paint to the sand-blasted
         brick surface.  See also 04211-14-R for additional guidance
         on painting brick.

    B.   The application of a water repellent or paint serves to
         protect the brick masonry against liquid water
         penetration while allowing water vapor to escape from
         within the brick.

    C.   The sealing of the outer surface of brick with a water
         repellent or paint may be necessary only when the
         exterior skin of the brick has been removed, often the
         result of sand-blasting.

         1.   Sandblasting is an abrasive method of removing
              dirt, stains, and paint from the surface of bricks;
              however, it is not recommended as it also removes
              much of the outer layer of the brick.  Sandblasting
              also erodes mortar joints.

         2.   By removing the outer layer of the brick surface,
              sandblasting exposes the inner more porous material
              to the effects of water penetration and pollutants.
              This increases the potential of water collecting in
              the pores, undergoing freeze/thaw cycles, and
              producing spalls in the brick.

    D.   Problems with Sealers:

         1.   May trap salt deposits within the brick creating
              potential for spalling if efflorescence is not
              removed before sealing.

         2.   May alter color of brick.

         3.   May make repointing or removal of dirt or
              efflorescence more difficult if surface is not
              cleaned before sealing.

         4.   See also 07180-01-S for additional information on
              sealers.

    E.   Safety Precautions:

         1.   Apply sealer or paint in a well ventilated area.

    F.   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).

    G.   For general information on the characteristics, uses and
         problems associated with brick, see 04211-08-S.

1.02 PROJECT/SITE CONDITIONS

    A.   Environmental Requirements:

         1.   Surface and air temperatures should be no less than
              50 degrees F. when applying sealer or paint.


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   Water Repellents (Sealers):

         1.   American Building Restoration
              9720 S. 60th Street
              Franklin, WI  53132
              414/761-2440

         2.   Diedrich Chemicals
              7373 South 6th Street
              Oak Creek, WI  53154
              414/764-0058
              800/323-3565

         3.   Hydrochemical Techniques, Inc.
              253 Locust Street
              Hartford, CT  06114
              203/527-6350

         4.   Hydrozo
              1001 "Y" Street
              P.O. Box 80879
              Lincoln, NE  68501
              402/474-6981

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

         6.   Thoro System Products
              7800 NW 38th Street
              Miami, FL  33166
              305/592-2081

         7.   Trocal
              Dynamit Nobel of America
              10 Link Drive
              Rockleigh, NJ  07647
              800/631-1668

         8.   V.I.P. Enterprises
              9690 NW 41st Street, Ste. 1
              Miami, FL  33178
              800/327-7479

    B.   Paint:

         1.   Sherwin Williams

         2.   Devoe

2.02 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 Cleaning:

         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).

              c.   Potential Hazards:  CORROSIVE TO FLESH.

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

         2.   Sodium Hypochlorite (NaOCl):

              a.   An unstable salt produced usually in aqueous
                   solution and used as a bleaching and
                   disinfecting agent.

              b.   Other chemical or common names include
                   Bleaching solution*; Household bleach*;
                   Laundry bleach*; Solution of chlorinated
                   soda*.

              c.   Potential Hazards:  CORROSIVE TO FLESH.

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

         3.   Detergent such as "Tide", "All" or approved equal.

    B.   For Sealing:

         1.   Solvent-based sealer with not less than 5% solids,
              but preferably more than 7%.  Try one of the
              following or approved equal:

              a.   "Old 200 Hydro-Seal" (American Building
                   Restoration)

              b.   "Diedrich 303-S Siloxseal Siloxane Water
                   Repellent" (Diedrich Chemicals)

              c.   "HT-101 Eon-Clad Water Repellent" (Hydroclean
                   - Hydrochemical Techniques, Inc.)

              d.   "PP/Hydrozo Clear Double 7" (Hydrozo)

              e.   "Tile & Masonry Protector" (ProSoCo, Inc.)

              f.   "ThoroClear 777" (Thoro System Products)

              g.   "Chem-Trete-Bsm" (Trocal)

              h.   "Ombrella Clear No. 9100" (V.I.P. Enterprises)

         NOTE:  See 07180-01-S "Types of Masonry Water Repellents"
         for a review of the characteristics of typical sealers.

    C.   For Painting:

         1.   Latex (water-thinned emulsion) Paint - either
              acrylic or vinyl latex suitable for use on brick:

              NOTE:  DO NOT USE OIL OR EPOXY-BASED PAINT AS THESE
              ARE NON-POROUS COATINGS AND WILL PREVENT THE
              MASONRY FROM "BREATHING".

              a.   Should be mildew and alkali-resistant.  

              b.   Acrylic latex paints are recommended over
                   vinyl acetate latex paints because the
                   acrylics are more alkali resistant.  Many are
                   self-priming so the same paint can be used for
                   both the prime coat and top coat.  

              c.   Latex paints can be applied to slightly damp
                   surfaces, though they must be absolutely clean
                   and free of any chalking paint.

              d.   All paint used shall be from the same
                   manufacturer and shall be appropriate for the
                   conditions encountered on the job site.  

         -OR-

              Cement-based paint for heavily pitted or cracking
              brick.

         2.   Masonry Conditioner for coating under latex paint
              such as "A5V2" (Sherwin Williams), "Wonder Bond
              16100" (Devoe), or approved equal.  

              NOTE:  USE SAME MANUFACTURER FOR BOTH LATEX PAINT
              AND MASONRY CONDITIONER.

              a.   The sealer will prevent the brick from
                   absorbing the water from the latex top coat
                   which would prevent the paint from adhering
                   properly.  

              b.   Conditioners/sealers are also alkali-resistant
                   and will prevent adverse chemical reactions
                   from occurring between the masonry and oils in
                   the paint.

         3.   Mineral Spirits (as recommended by paint
              manufacturer to thin conditioner):

              a.   A petroleum distillate that is used especially
                   as a paint or varnish thinner.

              b.   Other chemical or common names include
                   Benzine* (not Benzene); Naphtha*; Petroleum
                   spirits*; Solvent naphtha*.

              c.   Potential Hazards:  TOXIC AND FLAMMABLE.

              d.   Safety Precautions:

                   1)   AVOID REPEATED OR PROLONGED SKIN CONTACT.

                   2)   ALWAYS wear rubber gloves when handling
                        mineral spirits.

                   3)   If any chemical is splashed onto the
                        skin, wash immediately with soap and
                        water.

              e.   Available from construction specialties
                   distributor, hardware store, paint store, or
                   printer's supply distributor.

    D.   Clean, potable water

2.03 EQUIPMENT

    A.   Nylon bristle brushes

    B.   Soft bristle brushes

    C.   Garden hose

    D.   Paint rollers

    E.   Low-pressure spray equipment

    F.   Plastic bucket


PART 3---EXECUTION

3.01 PREPARATION

    A.   Remove all loose and crumbling mortar and/or brick to
         provide a sound surface.

    B.   Remove any efflorescence from the surface by dry brushing
         supplemented, if necessary, with clean, clear water.

    C.   Remove organic growth from the surface using a weed
         killer and clean, clear water.

    D.   Remove mildew and surface dirt:

         1.   Mix 3 oz. trisodium phosphate (TSP), 1 oz.
              detergent such as "Tide" or "All", 1 qt. 5% sodium
              hypochlorite (bleach) and 3 qts. warm water.

         2.   Apply solution to the brick surface and scrub with
              a soft bristle brush.

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

    E.   Repoint or recaulk as required before applying sealer.

3.02 ERECTION/INSTALLATION/APPLICATION

    NOTE:  SEALER OR PAINT MUST BE APPLIED TO A CLEAN SURFACE (SEE
    SECTION 3.01 PREPARATION ABOVE) TO BE EFFECTIVE.

    A.   For Sealer Application:

         1.   Apply sealer to a test area in an inconspicuous
              location.

         2.   Allow to cure for several months; Evaluate
              performance including color change, water
              permeability, etc.

         3.   When appropriate sealer is selected, apply sealer
              by brush or low-pressure spray with a rundown of at
              least 12 inches.  Follow manufacturer's
              instructions for precautions and special
              application procedures.

              a.   Apply sealer on dry days; Avoid treating
                   noticeably damp surfaces.

              b.   The transparent sealer or water repellent
                   should penetrate the brick to a depth of 1/8"
                   to 1/2".  

              c.   It works by changing the capillary angles of
                   the pores in the face of the brick wall from
                   positive (suction) to negative (repellency).

         4.   Allow to air-dry for at least 6 hours (length of
              drying time may vary depending on product used).

         5.   Apply a second coat of sealer as in 5. above and
              allow to dry.

         6.   Reapply sealer every 3-7 years.

    B.   For Paint Application:

         NOTE:  THIS METHOD PROVIDES A SURFACE COATING ONLY AND
         DOES NOT PENETRATE INTO THE BRICK.

         1.   Paint is best applied by brush, though rollers or
              spray equipment may also be used.

         2.   See also 04211-14-R for guidance on painting brick
              masonry.

3.03 ADJUSTING/CLEANING

    A.   Clean brushes and sprayers with white mineral spirits
         when the work is completed.

                         END OF SECTION