Hello,
 
I would appreciate your help with my following question:
 
I am about to purchase several Aluminum Outdoor Light fixtures for my
house. The house is located near the ocean, so I am concerned about
those fixtures holding up to the Sea Spray!
 
The fixtures I am interested in (according to the manufacturer) have
one protective layer and the color.
 
Do you think they will resist the Saltwater or will the metal beginn
to show these ugly white spots that sometimes appear on aluminum
items?
 
Thank you for your help!
 
Lars Dahlhaus

Hi Dasa,

Thanks for your question! Without knowing what the specific coating
you're referring to is, it's hard to tell you how effective it will
be. However, there are a number of websites which discuss the
corrosion of aluminum and aluminum alloys in salt water. The consensus
seems to be that some coatings can drastically reduce the effects of
corrosion; some of the documents below cite the best.

I searched "salt water" +aluminum +corrosion in Google and came up
with some of the following:

Corrosion of aluminum in sea water
http://www.abc.se/~m10354/publ/alu-corr.htm
Although this article, by an employee of Sikorsky (the helicopter
maker) has to do with the aluminum hulls of aircraft, you may find its
discussion of coatings and corrosion rates of use.

Corrosion of steel piping
http://www.gim.bnl.gov/misc/envtest/Gifs/seacorrosion.gif
This graph, from the Brookhaven National Laboratory, is not very easy
to read, but it shows the different corrosion rates for different
aluminum alloys in salt water (I don't know what your lamps are made
out of, but probably something similar, if not one of the things on
the chart, no?)

Finally, from the small island of Roatan, comes this dispatch:
http://www.roatanet.com/insights/news_june.htm
"Anything ferrous exposed to saltwater or salt atmosphere will
deteriorate very quickly. Saltwater will also have a deleterious
effect on non-ferrous metals like aluminum. They are subject to
corrosion and eventually become brittle. Aluminum cans thrown into
saltwater will completely dissolve in a very short time. Zinc-coated
(galvanized) surfaces will eventually yield to corrosive elements if
not properly maintained.

If you intent to install a metal roof on your home then I recommend
the alloy coated products similar to Gal-va-lume or the factory baked
enamel coated metal roofs that are also back primed. Be sure that any
field cut edges of metal roofing are re-coated with rust inhibitors."

Finally, the Navy report entitled Corrosion Prevention and Detection
(http://www.abm.rda.hq.navy.mil/CorrosionBook2a3.PDF) has a listing of
organizations working on corrosion issues toward the back. Even if
you're not interested in the highly technical information in the
front, this "webliography" can lead you to organizations who can
provide information on guarding against such corrosion.

I hope this is helpful! 

Libronaut

Thanks, for your help, it was very thourough. Although, I probably
need some more answers.

Also, when attaching your new fittings make sure you donīt damage the
protective coat and paint by scratching them.  Once the metal is
exposed "the rot sets in" so donīt slip with that screwdriver!

THX1138