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Historic Preservation - Technical Procedures

Spectitle:

Methods Of Bleaching Stains On Wood Floors

Procedure code:

0955001R

Source:

Ohj - Gordon Bock, 1-31-94

Division:

Finishes

Section:

Wood Flooring

Last Modified:

02/24/2012

Details:

Methods Of Bleaching Stains On Wood Floors



METHODS OF BLEACHING STAINS ON WOOD FLOORS


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on removing stains from
         wood floors using different methods of bleaching.  These
         methods include using household chlorine bleach, oxalic
         acid, or a concentrate hydrogen peroxide solution.

    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 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.   Denatured Alcohol:

         1.   Other chemical or common names include Methylated
              spirit*.

         2.   Potential hazards:  TOXIC AND FLAMMABLE.

         3.   Available from hardware store, paint store or
              printer's supply distributor.

    B.   Mineral Spirits:

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

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

         3.   Potential Hazards:  TOXIC AND FLAMMABLE.

         4.   Safety Precautions:

              a.   AVOID REPEATED OR PROLONGED SKIN CONTACT.

              b.   ALWAYS wear rubber gloves when handling
                   mineral spirits.

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

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

    C.   Chlorine Bleach:

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

         2.   Potential Hazards:  CORROSIVE TO FLESH.

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

    D.   Oxalic Acid (COOH)2 or (H2C2O4):

         1.   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.

         2.   One of the strongest organic acids.

         3.   Other chemical or common names include Dibasic
              acid; Ethanedioic acid; Acid of sugar*.

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

         5.   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.)

    E.   Hydrogen Peroxide (H202):  The concentrate solution used
         for wood bleaching - typically sold as a two-part kit
         containing sodium hydroxide.

         1.   An unstable compound used especially as an
              oxidizing and bleaching agent, an antiseptic, and a
              propellant.

         2.   Other chemical or common names include Peroxide of
              hydrogen*; Solution of hydrogen dioxide*;
              Superoxol*; (hydrogen peroxide is commonly sold as
              a 3% solution; Superoxol is a 30% solution;
              Superoxol causes flesh burns; 3% hydrogen peroxide
              does not).  THIS PROCEDURE CALLS FOR USE OF THE 30%
              CONCENTRATION.

         3.   Potential Hazards:  TOXIC (when concentrated);
              CORROSIVE TO FLESH; FLAMMABLE (in high
              concentration).

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

    F.   Clean, soft cloths

    G.   Clean, potable water

2.02 EQUIPMENT

    A.   Glass or porcelain container

    B.   Stiff bristle brushes

    C.   Sponges

    D.   Vacuum


PART 3---EXECUTION

3.01 PREPARATION

    A.   Wash wood using denatured alcohol to remove any dirt or
         other impurities from the surface.

    B.   Sand the wood and remove any paint or varnish.  Brush
         and/or vacuum dust and debris from the surface.

    C.   Remove any grease or oil from the surface by washing with
         mineral spirits and a clean, soft cloth.

3.02 ERECTION, INSTALLATION, APPLICATION

    CAUTION:  DO NOT MIX AMMONIA WITH CHLORINE BLEACHES, A
    POISONOUS GAS WILL RESULT!  DO NOT USE BLEACH ON BIRD
    DROPPINGS.

    NOTE:  TEST CLEAN A SMALL AREA BEFORE PROCEEDING WITH THE WORK
    TO DETERMINE THE BEST METHOD FOR REMOVING THE STAIN.

    NOTE:  TOTAL REMOVAL OF A STAIN MAY NOT ALWAYS BE POSSIBLE.
    IN THESE CASES, LIGHTENING OF THE STAIN MUST SUFFICE.  ON THE
    CONTRARY, BE PREPARED FOR BLEACHED WOOD TO APPEAR LIKE-NEW IN
    CONTRAST TO SURROUNDING WOOD THAT APPEARS MORE AGED.  

    NOTE:  BLEACHES ARE WATER-BASED SOLUTIONS AND TEND TO RAISE
    THE WOOD GRAIN WHEN APPLIED; THIS WILL REQUIRE SANDING UPON
    COMPLETION.

    A.   Stain Removal Using Household Chlorine Bleach:
         Recommended for removing an aniline dye finish and ink
         stains from wood.

         NOTE:  BE SURE TO PROVIDE PLENTY OF VENTILATION; USE
         PROTECTIVE GLOVES.

         CAUTION:  DO NOT MIX CHLORINE BLEACH AND AMMONIA.  THIS
         WILL PRODUCE A TOXIC GAS.

         1.   Apply bleach to the stained area using a clean,
              soft cloth or stiff bristle brush.  Use straight
              from the bottle; do not dilute.

         2.   Allow to sit on the surface for at least 10
              minutes; reapply if necessary.

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

         4.   Allow to dry for at least 24 hours before
              refinishing.

    B.   Stain Removal Using Oxalic Acid:  Recommended for
         removing blue ink stains, iron stains and darkening or
         blackening of wood due to age or previous cleaning.

         NOTE:  BEST TO USE IT WARM AND CONCENTRATED.

         1.   Dissolve crystals in hot water in a glass or
              porcelain container.

         2.   Apply the solution liberally to the surface using a
              clean, soft cloth or stiff bristle brush.

         3.   Allow to sit on the surface for at least 10
              minutes.  It may take longer (up to an hour) to
              achieve effective results depending on the type of
              stain and type of wood; agitate with a stiff
              bristle brush if necessary to aid in stain removal;
              reapply if necessary.

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

         5.   Allow to dry for at least 24 hours before
              refinishing.

    C.   Stain Removal Using Concentrated Hydrogen Peroxide (30%):
         Recommended for lightening woods or as a last attempt at
         removing a stain before resorting to replacement.

         NOTE:  HYDROGEN PEROXIDE AT THIS CONCENTRATE IS THE
         STRONGEST OF THE THREE BLEACHES LISTED.  IT IS TYPICALLY
         SOLD AS A TWO-PART KIT CONTAINING SODIUM HYDROXIDE.

         1.   Dampen the wood using a sponge soaked in clean,
              clear water.

         2.   Apply mixture of hydrogen peroxide and sodium
              hydroxide uniformly over the surface.  Follow
              manufacturer's recommendations for application
              procedures and dwell time.

                         END OF SECTION