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Historic Preservation - Technical Procedures

Spectitle:

Refinishing Polished Bronze Doors And Hardware

Procedure code:

0814001R

Source:

National Capitol Region Specifications

Division:

Doors And Windows

Section:

Bronze Doors & Frames

Last Modified:

04/11/2014

Details:

Refinishing Polished Bronze Doors And Hardware



REFINISHING POLISHED BRONZE DOORS AND HARDWARE


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on removing deteriorated
         lacquer from bronze doors and hardware and applying a new
         clear coating.

    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


 

PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.  Enthone Corporation        www.enthone.com

    B.  George Basch Company      www.nevrdull.com

    C.  StanChem Inc.     www.stanchem-inc.com

    D.  J.A. Wright & Co.     http://www.jawright.com

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.   Metal Cleaner:  Suitable cleaners are:

         1.   Nev-r-dull, (George Basch Company), or approved equal.

         2.   Incralac  (StanChem Inc.)    or approved equal

    B.   Standard Solvent: Mineral spirits, turpentine or denatured alcohol.

         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.

         Turpentine:

         1.   Typically used as a solvent and thinner.

         2.   Potential Hazards:  TOXIC AND FLAMMABLE.

         3.   Safety Precautions:

              a.   Work in a well ventilated area. 

              b.   Observe safety rules as turpentine is flammable, and the fumes can trip an                   ionization smoke detection system. 

              c.   Store soiled cloths in a metal safety container to guard against spontaneous combustion.

              d.   Available from hardware store or paint store.

                e. Turpentine is several times more expensive than Mineral Spirits.

         Denatured Alcohol:

         1.   Other chemical or common names include methylated spirits and ethanol.

         2.   Potential hazards:  TOXIC AND FLAMMABLE.

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

         4.   Denatured alcohol should be a satisfactory substitute for ethyl alcohol for stain removing purposes.

    C.   Alternative Solvents:

         1.   A pre-manufactured solvent that is a mixture of  mixture of 75% toluene, 24% acetone, and 1% butyl acetate.  (Casual users should NOT mix this in the field; this information is for professional and instructional reference only)

         2.   As an alternate, solvents can be utilized that are normally used for thinning nitro-cellulose lacquers, such as "DuPont Lacquer Solvent No. 3661-S" (for use in temperatures between 50 and 80 degrees F).

    D.   Inhibitor/Cleaner:  1% Benzotriazole solution in warm water (40 grams Benzotriazole/gallon of water).

    E.   Paint/Lacquer Remover:  Methylene chloride flush-away type remover, such as "S-26", (Enthone Corporation), or approved equal.

    F.   Mild Soap:  Ivory or a mild detergent with pH of approximately 8.0.

    G.   Clear Coating:  Acrylic lacquer containing acrylic ester resins dissolved in toluene with benzotriazole as corrosion inhibitor, such as "Incralac", (StanChem, Inc.), or approved equal.

    H.   Abrasive:  Silicon carbide abrasive pads, such as "Scotch-Brite", (3M Company), or standard commercially available pumice stone; or stainless steel wool.  DO NOT USE STEEL WOOL, WHICH MAY PROMOTE DISCOLORATION OF THE BRONZE.

    I.   Oxidizing Agent:  Aluminum chloride or liquid sulfur.

    J.   Diatomaceous earth abrasive such as "Wrights Silver Cream", (J.M.Wright & Co.) or approved equal.

    K.   Cloth:  Clean cotton waste.

    L.   Clean, potable water.

2.03 EQUIPMENT

    A.   For large areas of coating deterioration, bulk application with power spray equipment is more effective.

         The following equipment is recommended:

         1.   Spray gun, Binks or DeVilbiss with accessories; for example, DeVilbiss bleeder, external mix gun with cup, or approved equal.

         2.   Air compressor, small portable unit rated for this type of use

         3.   Accessories:  air hoses adequate for reaching all parts of the metal, couplers, repair kit for spray gun, small moisture traps.

    B.   Organic vapor masks, basic safety equipment to protect operator from breathing vapors or organic solvents during spray application.

    C.   Goggles, to protect operator's eyes from chemicals.

    D.   Gloves, neoprene rubber or polyethylene disposable gloves.  Skin contact with solvents (or Incralac in particular) should be avoided.


PART 3---EXECUTION

3.01 ERECTION, INSTALLATION, APPLICATION

    A.   Clean with mild soap and soft cloth, using fine
         abrasives, such as Wrights Silver Cream (a diatomaceous
         earth abrasive) and solvents, such as ordinary mineral
         spirits, only as necessary and lacquer light statuary
         bronze finishes on entrance door frames, transoms and
         sash, bronze grilles and light fixtures with acrylic
         lacquer.

    B.   Remove old lacquer, only if necessary, using lacquer
         remover applied with a cotton cloth wiped along the grain
         of the metal.

    C.   Allow the remover to stand on the lacquer for several
         minutes, then remove by wiping with a cotton cloth or by
         flushing with water.  Several applications of the
         stripper may be necessary in order to remove all traces
         of the lacquer from the metal.

    D.   Follow the stripping operation with an application of
         metal cleaner on a soft cloth, rubbing along the grain of
         the metal.

    E.   Persistent stains or badly corroded areas may be cleaned
         using an abrasive and standard solvent, such as a pad of
         fine bronze wool and plain mineral spirits.

    F.   All cleaner residue should be removed prior to the
         application of the clear protective coating by washing
         the metal surface at least twice with a standard solvent.
         This should be followed by a final wipe with the
         inhibitor/cleaner.

    G.   Clear coating is to be applied within 4 hours of
         cleaning.  It is not to be applied in inclement weather
         or when the relative humidity exceeds 60%.  The clear
         coating should be sprayed on using conventional spray
         equipment.  

         1.   Apply first coat in a thin mist.  Allow to dry a
              minimum of 30 minutes.

         2.   Apply four additional wet coats, allowing minimum
              thirty minutes drying time between each coat.

         3.   Minimum thickness of coating shall be 1 mil.

    H.   Final drying time will be 48 hours before the doors can
         be touched or used.

                         END OF SECTION