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Historic Preservation - Technical Procedures

Spectitle:

Applying A Clear Protective Coating To Yellow And White Bronze

Procedure code:

0501008P

Source:

National Capitol Region Specifications

Division:

Metals

Section:

Metal Materials

Last Modified:

02/24/2012

Details:

Applying A Clear Protective Coating To Yellow And White Bronze



APPLYING A CLEAR PROTECTIVE COATING TO YELLOW BRONZE AND WHITE
BRONZE


PART 1---GENERAL

1.01     SUMMARY

        A.   This procedure includes guidance on protecting exterior
             and interior architectural yellow and white bronze
             components with an applica= tion of lacquer.

        B.   For additional guidance on cleaning, refinishing and
             protecting bronze features, see 05010-03-R, 05010-05-P,
             05010-06-P, 05010-07-P, 05010-19-R, 05010-22-R, 05010-23-
             R, and 05010-24-R.
       
        C.   The refinishing and cleaning of bronze is highly
             specialized and should be conducted under the supervision
             of a metal conservator. The metals conservator should
             verify the use of all chemicals and treatments as a
             result of on-site testing to ensure protection of
             historic metals.

        D.   See 01100-07-S for general project guidelines to be
             reviewed along with this procedure. These guidelines
             cover the following sectio= ns:

             1.   Safety Precautio= ns

             2.   Historic Structu= res Precautions

             3.   Submittals

             4.   Quality Assuranc= e

             5.   Delivery, Storage and Handling

             6.   Project/Site Conditions

             7.   Sequencing and Scheduling

             8.   General Protecti= on (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= ).  

1.02     SUBMITTALS

        A.   Samples:  
       
             1.   All sample panels prepared by the Contractor should
                  be based on an existing sample in the building
                  which is considered by the metal conservator to be
                  close to the original architectural bronze finish,
                  as intended by the original Architect, and approved
                  by the Contracting Officer or the designated
                  representat= ive.  This existing sample, referred to
                  as the control sample, shall act as the reference
                  for all samples prepared by the Contractor.
             
             2.   The Contractor shall clean and refinish sample
                  areas on architectural bronze components included
                  in the work of this section as directed and for
                  approval by the Contracting Officer or the
                  designated representative and the metal
                  conservator.  Locations of sample panels to be
                  selected by the Contracting Officer or the
                  designated representative and the metal
                  conservator= .
             
             3.   Adjust the chemi= cal concentrations and
                  methodologi= es during test panel cleaning, as
                  directed by the Contracting Officer or the
                  designated representative and the metal
                  conservator= .

             4.   Sample areas shall be cleaned by the Contractor
                  using metho= ds and materials previously submitted
                  and approve= d.  Cleaning and refinishing sample
                  areas shall be performed in the presence of the
                  Contracting Officer or the designated
                  representat= ive and the metal conservator.
             5.   The Contractor shall obtain written approval from
                  the Contrac= ting Officer or the designated
                  representat= ive of bronze cleaning and refinishing
                  methods, materials, equipment used and sample
                  panels before proceeding with the work of this
                  section.  For this written approval purpose, the
                  Contractor shall allow a minimum of seven calendar
                  days after completion of sample cleaning to permit
                  the Contrac= ting Officer or the designated
                  representat= ive and the metal conservator to study
                  the sample panels for negative reactions.  Approved
                  sample panels shall be marked and left unaltered.
                  They shall be used as the standard for similar work
                  throughout the project.

1.03     QUALITY ASSURANCE

        A.   Qualifications:  The objectives of architectural bronze
             cleaning and refinishing are to remove dirt and grime
             without damaging the subst= rate and to give all
             architectural bronze a uniform appearance consistent with
             original finish, without blotches, streaks, runs, or any
             other kind of spotty appea= rance.
       
        B.   Certifications:  An independent metal conservator should
             be appointed to identify locations for sample areas and
             to monitor and review the samples prepared by the
             Contractor.

        C.   Field Samples:  Sample areas for every type of
             architectural bronze, as designated by the Contracting
             Officer or the designated representative, shall be
             prepared and shall establi= sh a standard for architectural
             bronze refinishing of that particular architectural
             bronze type and fabricatio= n.


PART 2---PRODUCTS

2.01     MANUFACTURERS

        A.   Stanley Chemical, Inc.
             401 Berlin Street
             East Berlin, CT 06023

2.02     MATERIALS

        A.   Clear Protective Coating:  Clear coating shall be
             commercially available acrylic type reversible coating
             such as "Incralac&quo= t; (Stanley Chemical, Inc.), or approved
             equal.

        B.   Flattening Agent:  Flattening agent for clear protective
             coating shall be commercia= lly available polyethylene
             dispersion (Stan Chem Inc.), or approved equal.
       
        C.   Water shall be clean, potable, non-s= taining and free of
             materials detrimental to all surfaces to be cleaned.
       
        D.   Cloth: Clean, cotton waste.
       

PART 3---EXECUTION

3.01     PREPARATION

        A.   Surface Preparation:

             1.   Clean surfaces to which protective coating is to be
                  applied.  See 05010-09-P for guidance.

             2.   Proceed with the following procedure within four
                  hours of cleaning.

3.02     ERECTION, INSTALLATION, APPLICATION

        THE METHOD FOR REFINISHING THE ARCHITECTURAL BRONZE WILL VARY
        DEPENDING ON THE TYPE OF ARCHITECTURAL BRONZE, AND THE METHOD
        DESCRIBED BELOW IS A PERFORMANCE SPECIFICATION FOR A TYPICAL
        REFINISHING PROCESS.  THE EXACT PROCESS WILL BE DEPENDENT ON
        PREPARED SAMPLES AND MUST BE DESCRIBED BY THE CONTRACTOR PRIOR
        TO COMMENCING WORK.  THE GENTLEST METHOD WHICH EFFECTIVELY
        CLEANS THE ARCHITECTURAL BRONZE SHOULD ALWAYS BE USED.
       
        A.   All superficial accretions, oils, and unreacted chemicals
             must be thoroughly rinsed from the surfaces prior to
             coating application using a non-ionic detergent.
             
        B.   Surfaces being treated must be thoro= ughly dried.
             
        C.   Apply clear protective coating by spray in three
             successive =AB mil, even coatings for a total dry thickness
             of 1-=AB mils, for interior finishes.  The exterior
             architectural bronze should be covered with a minimum of
             2 mil thickness of the clear protective coating.

             NOTE:  APPLICATION MUST FOLLOW THE CLEANING OPERATIONS
             WITHIN FOUR HOURS.  A= LLOW MINIMUM 20 MINUTES DRYING TIME
             BETWEEN COATS.
             
        D.   Brush-applying coating is not permit= ted.  (Brush-applied
             coatings will not provide complete coverage of uniform
             thickness.)
             
        E.   Add the flattening agent to the final coating to match
             the sheen of the original rubbed finish, as shown on the
             control sample and approved by the Contracting Officer or
             the designated representat= ive and metal conservator in
             the form of the Contractor= 's sample.

3.03     ADJUSTING/CLEANING
       
        A.   To be carried out by janitorial services, supervised by
             the Contracting Officer's representative.  Anything
             beyond cleaning should be referred to the metal
             conservator for immediate repair.
       
             1.   For regular monthly maintenance and cleaning of the
                  architectur= al bronze, apply a non-ionic detergent
                  to all surfaces using a sponge.
             
             2.   Thoroughly rinse the surfaces with water and dry
                  with a clean dry cloth.
             
             3.   Protect all surrounding materials from water
                  damage.

                         END OF SECTION