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Historic Preservation - Technical Procedures

Spectitle:
Cleaning Exterior Aluminum Features

Procedure code:
0574001P

Source:
Developed For Hspg (Nps - Sero)

Division:
Metals

Section:
Ornamental Aluminum

Last Modified:
02/24/2012

Details:
Cleaning Exterior Aluminum Features



CLEANING EXTERIOR ALUMINUM FEATURES


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on removing heavy
         deposits of soiling and oxide accumulations from
         aluminum.  Aluminum tends to weather to a dull light grey
         finish.

    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).

    C.   For general information on the characteristics, uses and
         problems associated with aluminum, see 05010-08-S.

1.02 SYSTEM DESCRIPTION

    A.   The surface layer of aluminum has a normal build-up of
         white aluminum oxide which can be rough and scaly in
         appearance.  Aside from this normal appearance, the
         aluminum surface should be free of dirt build-up,
         soiling, and other debris.


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   BASF-Wyandotte Corporation
         Chemical Specialties Division
         1609 Biddle
         Wyandotte, MI  48192
         313/246-6100

    B.   The Procter & Gamble Co.
         P.O. Box 599
         Cincinnati, OH  45202
         513/983-1100

    C.   ProSoCo, Inc.
         755 Minnesota Avenue
         P.O. Box 1578
         Kansas City,  KS  66117
         800/255-4255 or 913/281-2700

    D.   The Sherwin-Williams Co.
         101 Prospect Ave. NW
         Cleveland, OH  44101
         216/566-2000

2.02 MATERIALS

    A.   There are five categories of aluminum cleaners:  (See
         also 05010-12-S for additional information on aluminum
         cleaners)

         1.   Mild Soaps and Non-etching Detergents:  Non-ionic
              detergent such as "Joy" (Procter & Gamble Co.), or
              approved equal.

              a.   If a mild soap or detergent is gentle enough
                   to be applied with bare hands, it can be
                   safely used on aluminum without spot testing
                   first.

              b.   Automatic dishwasher detergents should be
                   always spot tested first.  Some of these
                   detergents can discolor non-finished and
                   anodized aluminum and can even bleach painted
                   aluminum.

              c.   Non-etching cleaners are acidic or alkaline
                   solutions containing inhibitors that permit
                   the cleaning of the metal without etching.
                   Care should be exercised in their use.

         2.   Solvent and Emulsion Cleaners:

              a.   These cleaners are relatively mild solutions
                   which can be used for removing dirt and stains
                   that cannot be removed by milder cleaners.

              b.   They generally can be used on bare, anodized,
                   conversion coatings, and porcelain finished
                   aluminum without spot tests, but product
                   directions should always be followed exactly.

         3.   Abrasive Cleaners:

              a.   These include polishes, cleaners, cleaner-
                    polishes, wax cleaners, scouring powders,
                   metal brighteners that contain abrasive
                   particles, and may also include water, oil,
                   wax, silicones, soap, acids or alkali.

              b.   These cleaners depend on vigorous rubbing
                   action along with a chemical reaction, and can
                   remove most dirt, stains, and corrosion
                   products from aluminum and will restore most
                   weathered aluminum surfaces.  

              c.   They are rated as moderate and heavy-duty.
                   Abrasive cleaners also include etching
                   cleaners, and special heavy-duty cleaners.

              d.   Household cleaners with coarse abrasives
                   should ONLY be used on aluminum with PORCELAIN
                   FINISHES.  Even a very fine abrasive can dull
                   a highly polished aluminum finish.  Fine
                   pumice powder and stainless steel wool (grades
                   0000 to 00) can be used with these cleaners,
                   but regular steel wool may leave rust stains.

         4.   Etching Cleaners:  Try "AC-266" (Sherwin-Williams),
              "Van Glo" (BASF-Wyandotte Corporation), or approved
              equal.

         5.   Special Duty Cleaners:  Try "Sure Klean Aluminum
              Cleaner" (ProSoCo, Inc.), or approved equal.

              a.   These cleaners should remove aluminum
                   oxidation, atmospheric dirt and carbon, and
                   other surface stains from all types of
                   aluminum surfaces.

    B.   Domestic soap flakes

    C.   Acrylate emulsion polish

2.03 EQUIPMENT

    A.   Garden hose and nozzle

    B.   Nylon bristle brushes

    C.   Light-weight scrubbing machine with nylon pads

    D.   Cellulose sponge mop or similar applicator

    E.   Heavy gloves and protective gear


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:  Avoid applying cleaning solution to exterior
         aluminum surfaces in direct sun, as these become very
         hot, and the detergent or soap solution will dry in
         streaks before it is possible to rinse them off.  These
         streaks can very easily become permanent and cannot be
         removed without abrasion.

3.02 ERECTION, INSTALLATION, APPLICATION

    NOTE:  IN CLEANING ALUMINUM, THE GENTLEST METHODS SHOULD BE
    USED FIRST.  MORE AGGRESSIVE METHODS SHOULD BE USED ONLY IF
    THE MILDER METHODS ARE NOT EFFECTIVE.  USING ABRASIVE METHODS
    WHEN NOT NECESSARY MAY LEAD TO THE REPLACEMENT OF AN ENTIRE
    SEGMENT.

    A.   Cleaning Heavy Deposits of Soiling:

         1.   Use a solvent-detergent mixture (BASF-Wyandotte
              Corporation, Sherwin Williams), or approved equal;
              or a mixture made with 1 oz. non-ionic detergent
              (nonyphenol condensate at 25%) and 1 oz. white
              spirit per gallon of water.  Agitate the mixture
              occasionally.

         2.   Apply mixture to aluminum using a clean sponge.

         3.   Rinse area thoroughly with clean, clear water and
              allow to dry.

    B.   Removing Loose Oxide Accumulations:

         NOTE:  ALUMINUM OXIDE IS DIFFICULT TO REMOVE FROM THE
         SURFACE OF THE METAL, AND AS SOON AS A FRESH SURFACE OF
         THE METAL IS EXPOSED TO AIR, THE METAL IS CONVERTED TO
         OXIDE.  SCRUBBING WITH A SOAP SOLUTION ALLOWS THE FRESH
         ALUMINUM SURFACE TO REACT WITH THE SOAP BEFORE THE AIR
         HAS A CHANCE TO OXIDIZE THE METAL, THUS PREVENTING
         FURTHER OXIDE BUILD-UP.

         1.   Mix a soap solution of 2-3 oz. of domestic soap
              flakes or 1/4 pint of liquid soap per gallon of
              water.

         2.   Scrub the aluminum surface with the soap solution
              using a light-weight scrubbing machine or nylon
              bristle brush.  

         3.   Rinse area thoroughly with clean, clear water and
              allow to dry.

    C.   Removing White Oxide Patches from a Smooth Aluminum
         Surface:

         1.   Mix a solution of 1/4 oz. of non-ionic detergent
              (nonyphenol condensate at 25%) per gallon of water.

         2.   Apply the solution using nylon bristle brushes if
              necessary to remove hard deposits.

         3.   If the surface is not too large, apply a very thin
              coat of diluted acrylate emulsion polish using a
              cellulose sponge mop or a similar applicator, or
              spray the solution on thinly.

              NOTE:  DO NOT APPLY THE ACRYLATE EMULSION POLISH
              UNLESS OXIDE HAS BEEN REMOVED BY CLEANING.

         4.   For highly corroded or stained areas, etching
              cleaners may be used, BUT ONLY ON BARE ALUMINUM, as
              etching cleaners tend to remove some of the metal
              surface.

              NOTE:  USE EXTREME CAUTION WHEN WORKING WITH
              ETCHING CLEANERS.  THESE ARE STRONG ACID AND
              ALKALINE BASED CLEANERS AND MUST BE RINSED
              THOROUGHLY AND NEUTRALIZED IF NECESSARY.

         5.   If the deterioration spots are tough, fine
              abrasives such as pumice powder and stainless steel
              wool grades (0000 to 000) may be used along with
              the etched cleaners.  DO NOT USE REGULAR STEEL
              WOOL, AS THESE MAY LEAVE RUST STAINS.

         6.   In some cases, it may be necessary to use special
              cleaners - which consist of all other cleaners that
              require special power (other than hand) equipment,
              such as steam cleaners, rotary wire brushes and
              abrasive blasting.

    E.   Removing Old Paint:  Paintwork on aluminum should be
         maintained annually.  All paint which is loose or flaking
         should be removed.  It is not normally necessary to
         remove all previous paint coatings if these are sound,
         hard and firmly adherent and are known to be conventional
         drying oil paint types, unless a sophisticated modern
         paint is to be applied such as two-pack epoxide resins.

                         END OF SECTION