Using Aluminum paint on steel

Anyone that knows anything about metals knows that when different metals contact each other, corrosion often occurs. For example,connecting a copper water pipe to a galvanized steel pipe without a dielectric union will cause excessive corrosion at that joint.
For years I have painted steel with Aluminum paint (silver colored paint), to make it appear shiny and still look like metal.
For some reason this paint became very hard to find in spray cans about two years ago. Stores like Walmart just stopped selling it. I immediately suspected some sort of ban on the stuff due to health or environmental reasons. This lead me to look on google to search for some sort of ban. I found no bans listed. However, in the process I discovered that this paint actually does contain small aluminum particles. (I originally thought the word "aluminum" just meant it was the color of aluminum, but now I know it really contains these particles.
This brings up another question. Since it contains actual aluminum, how come it don't cause a corrosive reaction when painted on steel? I painted my entire steel barn roof with this paint, since the steel was starting to rust in spots where the galvanized coating was wearing away from age. The paint lasted quite a few years, but I should repaint it soon again.
Since it's really aluminum, is it the paint resins or another reason that causes it to work on steel without any reaction?
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No. The Aluminun is less noble than the steel and therefor acts as an anode. (although probably to a very small degree)
-Waldo
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because the aluminum is coated with the non-conductive paint resins.
--
Jim Yanik
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wrote:

That's kind of what I thought.....
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On Thu, 21 Jul 2011 09:12:57 -0700, Smitty Two

Who the fuck are you? Are you the internet police? If you are, arrest me...... Be sure to bring a big gun, (you'll need it). If you donmt like what I post, DONT READ IT.... Actually you're just another usenet dickhead who wants the world to abide by his demands !!!!
And for the record, "aluminum paint" is fully on topic!!!
If you dont like my occasional joking around, then PLEASE KILLFILE ME. Unlike you, I'm not a boring person who lacks any sense of humor.
I'll do you a favor right now. You will be killfiled on my computer as soon as I finish this posting. Please do the same.... PLONK!
jw
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snipped-for-privacy@myplace.com wrote the following:

According to the Rustoleum site. http://www.rustoleum.com/CBGResourceCenter.asp?sn 2
It seems they say to use aluminum primer to galvanized metal before any other spray paint is used.
    Can aerosol paints be applied to galvanized metal? A     Yes, if Aluminum Primer is used as a base coat and allowed to dry for 24 hours before applying aerosols. Most all of our spray paints are oil-based enamels. If applied directly to galvanized metal without the primer, the oil in the paint will react.
--

Bill
In Hamptonburgh, NY
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wrote:

Good link, thanks for the reply. I'll have to check on this primer before I paint that roof again. I should mention that I never noticed any reaction to the metal from the oil in the paint.
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snipped-for-privacy@myplace.com wrote the following:

http://www.discountpaint.net/store/product.php?productid 997&gclid=CKHqlPGsk6oCFYaD5QodGgfCzw
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Bill
In Hamptonburgh, NY
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On Jul 21, 3:33am, snipped-for-privacy@myplace.com wrote:

For real corrosion protection in industry, zinc-rich paints are used. Zinc has the unusual property of being able to be formulated as high as 90% zinc content in such paints. Typical uses are over welds in manufactured chain link fence gates, for example. Aluminum doesn't even come close. Aluminized steel is a hot dip somewhat like galvanizing.
Joe
Joe
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Galvanizing IS zinc. I guess I have not heard of zinc paint. I'd guess that would be ideal for galvanized steel which has lost most of it's galvanizing. Where does someone buy that stuff?
Thanks
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