Care should be taken when applying coatings of any kind (e.g., paints, sealants, and cleaning agents) to building exteriors so that the solutions or emulsions used do not cause damage to other building components. This is especially true for architectural aluminum components, such as window and door frames, store fronts and entrances, curtain walls, mullions, columns, and hardware.

Corrosion Happens

Aluminum has a high strength-to-weight ratio, which makes it ideal for commercial construction. However, it is naturally vulnerable to surface staining and corrosion, which can ruin its appearance and compromise long-term durability. Aluminum fenestration manufacturers thus rely on highly engineered finishes to provide protection. Such finishes provide excellent protection against environmental attack but not necessarily from coatings and other materials used by other construction site trades.

If the finish is damaged in any way, the potential for corrosion will greatly increase. Any such defects must be addressed in accordance with the applicator’s and/or supplier’s recommendation as soon as possible. Damaged aluminum finishes are extremely difficult, if not virtually impossible, to fix in the field and must typically be replaced — often a costly proposition. Prevention is the key.

Tricks of the Trade

After the fenestration components are installed, their protection generally falls under the jurisdiction and responsibility of the general contractor. Depending on contract details, the liability for damage could be passed on to various subcontractors who use the incompatible materials.

It is good installation practice to inspect completed work on a daily basis along with the general job superintendent. Any damage that occurs after the inspection can then be readily identified and clearly defined as to cause and responsible party.

In general, fluid construction products, including spatter or run-down of coatings or cleaner (from any operation) to adjacent or lower portions of the building, should be minimized and removed as soon as possible. Metal seams, crevices, sills, and any other area that may trap water, chemicals, or dirt must be cleaned and thoroughly dried. The exact procedure will vary depending on the nature and degree of contamination. Cleaning should be done during periods of mild temperatures on a shaded side of the building or on a cloudy day.

Never use aggressive alkaline or acid cleaners on aluminum finishes. Do not use cleaners containing trisodium phosphate, phosphoric acid, hydrochloric acid, hydrofluoric acid, fluorides, or similar compounds on anodized aluminum surfaces. Strong solvents or abrasive cleaners can cause damage to painted surfaces. Always follow the cleaner manufacturer’s recommendations as to the proper cleaner and concentration, and test-clean a small area first.

Applied With Care

In general, applying liquid products to building exteriors should be done with care so as not to damage nearby materials. Fixing a problem shouldn’t create a new one!

Rich Rinka serves as the technical manager, Standards & Industry Affairs, at the American Architectural Manufacturers Association (AAMA). Prior to coming to AAMA, Rinka worked in the industry as a field technical engineer for a component supplier and also served as chair of the AAMA 800 Maintenance Committee. During his time in product development for the automotive industry, he developed and still holds four patents related to sealants. For more information, contact: AAMA, www.aamanet.org