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Historic Preservation - Technical Procedures

Spectitle:

Applying Benzotriazole (Bta) To Bronze

Procedure code:

0501007P

Source:

Outdoor Sculpture Manual - Center For Public Buildings

Division:

Metals

Section:

Metal Materials

Last Modified:

12/18/2013

Details:

Applying Benzotriazole (Bta) To Bronze



APPLYING BENZOTRIAZOLE (BTA) TO BRONZE


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on applying
         Benzotriazole (BTA) to outdoor bronze in order to inhibit
         corrosion of the metal.  This procedure is primarily
         intended to follow the removal of barrier coatings, such
         as wax or Incralac, prior to recoating.

         NOTE:  BTA is regularly applied to bronze as an additive
         to wash water.

    B.   For general information on the characteristics, uses and
         problems associated with bronze, see 05010-03-S.


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.   Benzotriazole (BTA), such as "Cobratec" (GAF
         Corporation), or approved equal

    B.   Ethanol:

         1.   Other chemical or common names include Ethyl
              alcohol; Ethyl hydroxide; Ethylic alcohol; Methyl
              carbinol; Cologne spirits*; Fermentation alcohol*;
              Grain alcohol*; proof spirit*; Rectified spirit*;
              Spirits of wine*.

         2.   Potential Hazards:  FLAMMABLE; moderate toxicity if ingested, inhaled, or by skin contact; (see CAMEO Material Database,                           Museum or of Fine Arts, Boston, for more information).

         3.   Available from chemical supply house, hardware
              store or liquor store.

         4.   Denatured alcohol, which carries no liquor tax,
              should be a satisfactory substitute for ethyl
              alcohol for stain removing purposes.

    D.   Clean, potable water


PART 3---EXECUTION

3.01 ERECTION, INSTALLATION, APPLICATION

    A.   Wash the bronze surface to remove loose dirt and allow to
         dry.

    B.   Mix a 2 to 1 solution of water:ethanol.

    C.   Add a 3% solution of BTA to the water-ethanol mixture.

    D.   Brush the solution onto the bronze and allow to dry for
         one hour.

    E.   Brush apply a second coat of the solution and, again,
         allow to dry for one hour.

    F.   Rinse the surface thoroughly with clean, clear water from
         top to bottom to remove excess, crystallized BTA.

    G.   Allow the surface to dry for 48 hours before any
         additional treatments.

                         END OF SECTION
 


bronze, benzotriazole, Incralac, outdoor bronze, bronze corrosion