Volume 35, Number 5, May 2000
Painted and Anodized Finishes
critical care and
by John McGill
Many people prefer to avoid exercise, maintenance and housekeeping, yet for those who make the time, the rewards are many. Nowhere is this truer than with painted or anodized aluminum installations which require care and protection before, during and after installation to keep them looking good.
Both painted and anodized finishes possess exceptional resistance to corrosion, discoloration and wear. However, harsh chemicals, abuse or neglect can damage the aesthetics of the finish. In addition, surfaces exposed to the atmosphere will collect varying amounts of soil and dirt, depending upon geographic area, environmental conditions, finish and building elevation. Periodic maintenance will help to prevent the long-term accumulation of soil, which can accelerate weathering. More frequent cleaning of finished aluminum that is exposed to harsh marine environments or located in heavy industrialized areas is particularly important.
Architectural aluminum products should be protected from damage at the job site during and after installation. Cement, plaster, terrazzo, alkaline and acid-based materials used to clean masonry are very harmful to finishes, and should be removed with water and mild soap immediately to avoid the possibility of permanent staining. After installation, the building owner should set up a regular maintenance program.
The following guidelines should be followed when cleaning architectural aluminum surfaces.
Light Surface Soils
Removal of light surface soil may be accomplished in several ways. The simplest procedure is to flush the metal with water using moderate pressure to dislodge the soil. If the soil still adheres, then a mild detergent should be used with a brush or sponge. Additional precautions to follow when cleaning painted and anodized surfaces include:
Do not use abrasive household cleaners, steel wool, hard brushes or excessive
and abrasive rubbing that can wear, damage or dull
Avoid drips and splashes and remove run-downs as quickly as possible;
Do not use strong cleaners on glass and other components where they might come into contact with the aluminum;
Avoid temperature extremes. This can accelerate chemical reactions, evaporate or strengthen cleaning solutions, cause streaking, staining or blotching. Ideally, cleaning should be done in the shade at a moderate temperature;
Never use paint removers or aggressive alkaline, acid or abrasive cleaners;
Always test a small area first and follow manufacturer recommendations for mixing and diluting cleaners;
Make sure cloths, sponges and cleaning equipment are free of grit.
Cleaning procedures to remove construction or accumulated environmental soils and discoloration should be initiated as soon as possible. Mortar, cement and other alkaline materials will corrode anodic coatings quickly if allowed to dry on the metal surface.
If surface soil still adheres after using the above cleaning procedures, then more aggressive methods may be necessary depending upon whether the finish is painted or anodized.
Removal of Stains
For painted finishes, more aggressive methods may be required if the light cleaning does not completely remove the residue:
Sodium hypocholorite solution (laundry bleach, Clorox) may assist in removing certain stains from painted finishes;
Hydrochloric acid or 10 percent muriatic acid, diluted with 10 volumes of water,
may assist in removing rust or alkali mortar stains from Fluropon (a registered trademark
of the Valspar Corporation) or Duranar (a registered trademark of PPG)
Limit contact to 5 minutes. Flush all surfaces with water immediately after use;
Anodized surfaces should not be washed with acidic or caustic solutions.
Removal of Stains
Once the general cleaning procedures have been exhausted on your anodized finish, cleaning with an abrasive pad soaked in clean water or a mild detergent cleaner may be tried.
Using uniform pressure, hand scrub the metal surface using a palm-size nylon cleaning pad. Thoroughly wet with clean water and a mild detergent cleaner or pumice powder;
After scrubbing, the surface should be rinsed thoroughly with clean water or wiped with solvent to remove all residues;
A power cleaning tool, such as an air-driven reciprocating machine fitted with cleaning pads, may be necessary for removal of unusually heavy soils. During this operation, the surface being cleaned must be wetted continually with clean water or a mild detergent solution;
If it is necessary to remove oil, wax, polish or similar materials from anodized finishes, MEK, mineral spirits or an equivalent solvent is recommended.
Removal of Non-Water
Mild solvents such as mineral spirits may be used to remove tar, grease, oil, paint, graffiti and other non-water soluble deposits. However, extreme care should be used when using solvents on a painted surface. Many solvents will reduce the gloss level of painted finishes and, if allowed to remain on the finish for more than a few minutes, may soften the paint and damage the coating. It is recommended that the coating manufacturer be consulted prior to using a solvent. It is also recommended that the painted area that comes into contact with the solvent be limited as much as possible. Always test a small, concealed area first.
For more detailed information consult one of AAMAs cleaning guides, or visit its website at www.aamanet.org. Also available is Kawneers Architectural Aluminum Finishes brochure.
John McGill serves as marketing manager for Kawneer Companys entrance product line and is based in Norcross, Ga. Glaziers Guild appears monthly with rotating authors.
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