Historic Preservation - Technical Procedures

Repairing Brass Window And Door Finish Hardware
Procedure code:
Hspg Prepared For Nps - Sero
Doors And Windows
Finish Hardware
Last Modified:
Repairing Brass Window And Door Finish Hardware
Last Modified:


Repairing Brass Window And Door Finish Hardware

Procedure code: 0871004R



    A.   This procedure includes guidance on repairing brass window and door hardware where these have become deteriorated, corroded, and where there are missing elements.  For guidance on cleaning brass hardware, see 05010-03-P and 08700-02-R.

    B.   Safety Precautions:

         1.   All workers must be protected from the effects of chemicals during the cleaning/repairing operations.

         2.   Some chemicals suggested for brass maintenance are flammable, toxic, or both.  As a general rule, avoid skin contact and inhalation of any chemical.              Rubber or plastic gloves should be worn when handling hazardous (flammable or toxic) chemicals. Read the MSDS, follow storage and handling procedures printed on the container labels of the cleaning solutions, provide good ventilation while working, and thoroughly wash hands after completion of the work.

         3.   Workers should take precautions to prevent epoxies and their component parts from contacting the skin. Provide PPE including protective clothing which must be worn, and protective creams applied to exposed skin areas.  Accidental skin contact with epoxies and their component parts must be treated immediately by washing the affected area with soap and water, never with solvents.  Exercise care to avoid skin contact with tool cleaning solvents, and provide adequate ventilation for clean-up operations.

    C.   Historic Structures Precautions:

         1.   As with all other historic fabric, brass can have historic importance that must be identified at an early stage.  The item's merit, in terms of age, uniqueness of design, materials, size, technological development, association with persons or events, exceptional workmanship or design qualities, all must be understood before decisions regarding repair, maintenance and preservation can be made. 

         2.   Existing brass hardware components must be removed without damage to the material itself, adjacent materials, or substrate.  These will then need to be carefully labeled as to their original location and orientation (old-fashioned tags with strings work quite well for this).  Storage inside re-sealable zipper storage bags with any documentation or accessioning information inside with the component is a popular method out in the field, but depending on the chemical makeup of the storage bag, the parts may need to be wrapped in acid-free paper first (check with the RHPO or a trained conservator for guidance).  Before components are reinstalled, they may need to be cleaned, repaired, restored and/or refinished by a trained conservator.

         3.   When choosing the brass hardware to be replaced, the RHPO should be consulted to provide information about how to match for color and type of the metal. The terminology used for designating brass finishes has undergone significant changes in the last few decades, and any possible specification discrepancies in older technical data will need to be identified before moving forward. 

A cross-reference chart between old/new finish designations may be found as ���Complete ANSI / BHMA Numbers for Materials & Finishes��� online at  http://www.builders-hardware.com/files/Complete%20Finish%20Chart.pdf

You can read more about metal finishes on the website of the National Association of Architectural Metal Manufacturers (NAAMM), where their Metal Finishes Manual may be downloaded from http://www.naamm.org/landing_pages/AMP_500-06_PDF.htm


    D.   See 0110007S 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).


    A.   Brass is an alloy of copper and zinc.  The color varies based on the amount of zinc used and which other metals are added.  Brass with more zinc is yellow in color, while adding a bit of aluminum will creates a light golden color.  Brass that has  manganese added produces a ���bronze��� color, while adding nickel results in a whitish compound with a high density, good corrosion resistance and a long wear-life known as ���nickel silver���.


    B.   Brass is a hard, durable, and utilitarian metal which makes excellent castings.  It can be worked hot and extruded, and by adding a small amount of lead during its manufacture brass becomes very malleable.  Brass is commonly extruded, especially to produce large architectural pieces such as doors and elevator parts, and in elements such as window frame sections, hand rails, and balustrades. Brass has also been traditionally used for architectural and marine purposes because of its corrosion resistance.


    C.   In colonial America, public buildings and fine homes often had brass hinges, door knobs, door knockers, chandeliers, and fireplace and irons; however at that time almost all of the brass hardware was imported from England.  In time,          America began manufacturing its own brass, utilizing it for light and plumbing fittings and fixtures, and a wide variety of builder's hardware.  Polished brass was a favorite for commercial buildings handrails, stair railings, elevators, lobby furniture, building       directories, etc.


    A.   The natural beauty of the brass should be carefully preserved. Hardware should be intact and in good condition, without any signs of deterioration (such as corrosion by the action of the atmosphere, or acids derived from organic growths, scaling, pitting, etc).  Fittings should have no missing elements, should be securely mounted, properly set in the window or door frame, and there should be no indication of movement when pushed or pulled.  Any protective coating on brass needs to be continuous for it to be effective, and should not allow bare metal to be exposed though poor maintenance, peeling or wear.


    A.   Packing and Shipping:  For replaceable material: protect brass hardware from damage at all times during handling, installation, and operation of the building.

    B.   Acceptance at Site:

         1.   New metal parts shall be delivered on the job carefully packed.  Inspect each piece immediately before installation, and do not use pieces which have observable surface damage.

         2.   Manufacturer's delivery or job markings on the brass, and adhesives for manufacturer's labels, shall either be a neutral or slightly acidic material.  In no case shall such material be alkaline, as staining of the metal will result and will be cause for the rejection of the piece.

    C.   Storage and Protection:

         1.   Brass hardware should be stored so as to protect it from surface damage at all times.  It needs to be carefully packed and should remain so from the time of delivery until installed.  Keep uninstalled metal components in a dry, secure storage facility.

         2.   Salvaged historic material shall also be carefully packed and stored under cover in a dry, secure storage facility, preferably in the building away from working or traffic areas.  Mark salvaged material with the date of removal (as detailed in 1.01, C, 2 above.)


    A.   Preventive Maintenance and Repair activities should be scheduled during appropriate environmental conditions to avoid weather related failures.

    B.   When cyclical maintenance work requires the use of high ladders and other access equipment, cluster the performance of as many work items as possible.



    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 cleaning and stain removal work, and these products should be purchased when available, as they tend to be less expensive. 

    A.   Hardware:

         1.   Butt hinges complete with all necessary screws

         2.   Mortise locks and latches complete with lock body, rose, spindle, knobs, key plate, latch and strike plate, and any other trim including all necessary screws and fastenings.

         3.   Sash lifts and locks complete with all necessary screws

         4.   Sash counterweights complete with track, pulley, cord/chain, weights and all necessary screws

         5.   Metal thresholds complete with all necessary counter-sunk screws

         6.   Spring brass weatherstripping fit for the purpose, such as 1-1/8" x .008" size, with hemmed edges complete with screws or springs   

         7.   Replacement screws and bolts

    B.   Emery paper, sandpaper (useful for smaller jobs or final feathering of high paint edges, corners, or hard to reach places), or fine steel wool.

    C.   Mineral Spirits:

             1.   A petroleum distillate that is used especially as a paint or varnish thinner.  It was developed as an inexpensive replacement for the vegetable-based turpentine, and is a light version of kerosene. It comes in three grades, and cost rises as refining quality increases.

             2.   Other chemical or common names include Benzine (not Benzene); Naphtha; Petroleum spirits; White spirit; Varisol; Solvent naphtha; Stoddard solvent.

             3.   Potential Hazards:  TOXIC AND FLAMMABLE.

             4.   Safety Precautions:

                  a.   Work in a well ventilated area.

                  b.   ALWAYS wear proper PPE such as rubber gloves, safety glasses/goggles and a properly rated respirator when handling any solvent such as mineral spirits.

       c.   AVOID REPEATED OR PROLONGED SKIN CONTACT.  If any chemical is splashed onto the skin, wash immediately with soap and water.

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

             2.02 EQUIPMENT

    A.   Wiping cloths

    B.   Eye and skin protection

    C.   Gloves and protective gear

    D.   Brushes

    E.   Putty knife

    F.   Scrapers   

    G.   Wire brush

    H.   Screwdriver

    I.   Electric drill

    J.   Electric wire brush



    A.   Determine the cause and extent of the problem.  Determine the age of the hardware and examine the condition of the entire surface.  Inspect for:

         1.   Wear, especially at moving parts.

         2.   Parts which have failed, or which are unsecured, broken, cracked, missing, distorted, or loose (especially check screws and bolts).

         3.   Paint - coating failures such as chips, peeling, checks, bubbling, and wear.

         4.   Rust corrosion, which can be caused by a reaction to moisture, deicing salts, acids, soils, gypsum plasters, magnesium oxychloride cements, ashes, clinkers, and sulfur compounds.  Determine the source of the moisture which causes the deterioration and eliminate it.

         5.   Determine if the brass hardware can be salvaged. Consultation with a qualified conservator may be necessary.

         6.   Measure and record the dimensions of the various metal parts needing replacement.


    A.   Protection: Brass hardware should be removed for repair. You should not attempt to repair or restore it in place unless a qualified conservator is engaged.

         1.   Protect all surrounding areas and surfaces during application of rinsing solutions and against the spread of dust, debris, and water.

         2.   All methods of enclosure and protection should be approved by the project supervisor.  Protection should consist of non-staining plastic sheets, tarpaulins or burlap, secured to prevent lifting in high winds.

    B.   Surface Preparation:

         1.   Good surface preparation is essential for the proper adhesion of a protective coating following cleaning/repair operations.  To achieve this, the protective coating must be applied to a firm, stable foundation that is free of contaminants (such as grease or water soluble salts).

         2.   Degreasing: This removes oil or grease to avoid spreading the contamination over a wider surface. Non-caustic degreasing agents are available, or surfaces may be wiped down with a succession of clean cotton cloths or swabs dipped in pure mineral spirits.  Afterward, wash the features using warm water and detergent followed by a thorough water rinsing. 


    A.   Repair Due to Corrosion: Brass, like copper, is corroded by exposure to moisture, acidity caused by polluted or salty air or newly-cut wood, chlorides, acetates, and ammonia.  Excrement from birds or other animals is acidic and can also damage brass.

         1.   Lightly corroded areas due to moisture and/or standing pools of water, where the brass has not thinned, can be wiped and dried.  If traces of rust from other nearby or underlying materials are visible, remove the stain first with emery paper/ emery cloth.  Next clean the brass object, dry it completely, and apply a protective coating. 

a. For guidance in cleaning tarnished brass, see 0501032R. 

b. For guidance in applying a clear protective coating to brass features, see 0501008P. 

c. For guidance in cleaning brass features, see 0501003P and 0501010P.

                        d.    For guidance on cleaning door hardware see 0870002R.

                    2. Perforated spots and any thin areas surrounding them can be soft soldered or brazed with a patch cut to cover the affected area. Do not attempt this work without seeking instruction or the services of a qualified conservator.  For further guidance on repairing dents, scratches, holes, nicks and other minor imperfections, see 05010-02-R.

    C.   Missing pieces:  Missing pieces can be reproduced by casting duplicates of undamaged parts you already have.  See 0870001R for guidance on replicating hardware.

    D.   Deterioration of Protective Coating:

         1.   Corrosion usually begins as breaks in the surface and then spreads beneath it.

         2.   To correct this, you will need to completely remove the protective coating from damaged elements and any rust staining that is present, using the appropriate tools listed in the 'materials' section of this TP or under the direction of a qualified conservator. 

a. For guidance in removing paint or lacquer from brass features, see 0501031R. 

b. For guidance in reapplying a clear protective coating to brass features, see 0501008P.

    E.   Other brass item repairs.

a. For repair work specific to brass pulleys, brass chains and window sash weights, see 0876001R. 

b. For repair work specific to hinges, see 0871201R and 0871202R.

    F.   Re-installation of hardware:

         1.   Check function of hardware against job site documents, conditions and interferences.  Adjustments and/or substitutions shall be made only as authorized.

         2.   Work shall be by skilled tradespeople working with the proper equipment.  It shall fit the work of others accurately, shall be applied securely, and adjusted properly.  Care will be exercised not to damage adjacent surfaces.

                         END OF SECTION



Last Reviewed 2015-02-02