UPDATE:  New information regarding painting aluminum has been added to this column. Be sure to check the Author's Notes following the article.

Oil to the Rescue

Did you know that paint companies employ chemists? These individuals know that you must create a barrier between the oxidized aluminum and the water based acrylic finish paint. It is easy to do.

Virtually every paint manufacturer makes a high quality oil based metal priming paint. This is the product to use to create the barrier. However, it is not necessary to apply the primer full strength. In fact, thinning it down actually helps the primer penetrate more deeply into the eroded paint finish on your siding.

The trick is to thin one gallon of paint with one pint of thinner. Be sure to use the approved thinner! Don't use gasoline, or some other solvent you think will work. The label on the paint can usually will tell you exactly what to use.

Surface Preparation

The key to any successful painting job lies in preparing the surface. The surface to be painted is the foundation. Poor foundations create poor results. This is true in any project.

Clean surfaces are the key. If you remember that paint is simply a modified glue, you will be on the right track. Glue likes to stick to rough surfaces - there is more surface area. Glue doesn't like dust. If you follow some of my painting tips, your upcoming paint job will last and last!

Manufacturers of Acrylic Aluminum Siding Paint

• Benjamin Moore
• Duron
• Glidden Paint
• Kurfees
• Porter Paints
• Sherwin Williams

NOTE:

To learn more about painting aluminum siding, read these highlighted articles.

Author's Notes: The following updated information was received from the Paint Quality Institute.  Debbie Zimmer addresses ammonia in latex paints and the resulting bubbling.

"Hi Tim,

Thanks so much for your questions and comments.  Regarding ammonia in latex paints, it is so low today that the off gassing (resulting in bubbling) is really not a factor.
 
Here are a few detailed points to consider:
 
1. Bare Aluminum: forms a strong oxide layer which is easy to stick to and is relatively inert to ammonia. Some folks confuse ammonia with acid. Yes --- acid will generate some hydrogen gas but there should not be a reaction with ammonia.
 
2. All Aluminum Siding is coated. This again generally results in a surface that is easy to stick to but for all intents and purposes, relatively inert to waterbased paints. Even under poor conditions, incidental exposure to Aluminum should not be a problem because of above (1).
 
Also, on occasion, we do speak about oxygen bleach but typically use the more common (common to homeowners) "bleach" term.  Perhaps we should use oxygen bleach more often.  We don't use brand names (in any of our materials), such as Clorox.
 
Tim, I'm really glad you asked the questions --- it helps us make our educational information stronger.
 
If you are ever in the Philadelphia, PA area, I would love to take you on a tour of our PQI facilities --- we have over 30,000 paint panels on exposure (a few dating back to the '50's) and 1000's with the most recent and forward looking technologies. In addition, our "farm" contains over 200 different surfaces and substrates (painted/not painted) on exposure as well.
 
Thanks again,"
Debbie Zimmer
PQI Director of Communications and Alliances
Dow Coating Materials, North America
The Dow Chemical Company

Updated: 08/23/2010

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