Alumunium protection

Hi there,
Apart of anodizing aluminum or powder coating aluminum, is there an other way to protect it from weather and salt water sea conditions. Bert

 

I suppose the obvious one is paint. I think I prefer un-painted though, it is not unknown for the unscrupulous to "hide a multitude of sins", which includes corrosion damage, beneath paint and filler. Bare, it is easier to see faults.

 

Thank you Mr Efficiency. Maybe there was something I had never heard about it. Yes, painting is a solution, but then I would use Zinc spray from a German company Wurth. I have good result on my gates, trailer, etc at home. Zinc on Aluminum in salt air conditions, although not in the seawater, I m wondering. Bert

 

Most builders leave it bare. Aluminum has it's own oxide coating that protects it very well. Coating it or painting it, to be done right, requires an involved process of cleaning and etching to get rid of the oxide so the coating will bond to the metal. Once the coating is penetrated the aluminum will corrode.

 

There are probably some circumstances where painting extends the life, one would be trailer fishing boats where lead sinkers and brass swivels can find their way down into inaccessible places and cause corrosion through the 'dis-similar metals' route. Many boats have had holes put in them over time, but if well painted on the inside, there is an effective barrier against it.

 

I am living 800 meter from the sea and many items from aluminium which are painted, is getting a funny snow/grey white oxidation. You probably right Ike. The natural oxidation is different. I will keep it natural. Thanks. Bert

 

Anodizing or something similar is something you can do yourself, but my memory is getting a bit hazy. I think it involves etching with an NaOH solution, rinsing and subsequent bathing in oxalic acid. True anodizing is also possible, using a carbon pile soaked cotton wool and a power source; you will get a hard oxide layer but it may not look nice because the current determines the surface properties.

 

Indeed CDK, I still have the information from Practical Boat-Owners, an English magazine, page 66 March 2012, which had an excellent simple very well detailed article, with photo's and examples on how to make an anodizing electrical bath from simple parts, even if one like to use a colour, added to the anodizing.

My "toilet bowl" is finished and maybe I can find the time to make a bath. Although my 4 m2 solar panels, the reason why I added an extension to the transom, needs my priority. At the end, I may use stainless steel, I will see. Bert

 

Last year I restored a set of aluminum alloy wheels (they were corroded, though not terrible and the factory coating had failed in spots after 17 years) using a product called POR-15 Glisten. I had heard some good and some bad about this product. I followed the metal preparation and application instructions exactly. After the most difficult winter in recent memory here in the northeast USA my wheels look every bit as good as they did last fall when I restored them.

I'll post a link for you below. When you get to Amazon you can find a lengthy review that I did on the product at the Amazon site.

http://www.amazon.com/GLISTEN-CLEAR...qid=1396829665&sr=1-1&keywords=por 15 glisten

 

The best protection is using the right alloy. It makes the single largest difference. 5083, 5086, 5053 alloys are great places to start. Then careful corrosion measures like zincs or active measures like the mercathode system are things to consider.

 

Some good schooling on aluminum in here. Thanks guys.

Ah, & as a small contribution. When I've had aluminum to coat/re-coat in the past, I used Vinegar (aka Acetic Acid) instead of Oxalic, or something heavier duty (more corrosive). And it worked out fine. [It was a lot kinder on my hands & favorite work jeans too, as a perk ;-) ]
After the acid wash, I gave the metal a couple of coats of self etching primer, & then some Interlux "1-part" LPU.

The parts weren't subject to super high wear, but held up well. And the cost was right.
Though doubtless, anodizing is tougher. Ditto on some of the "spray & bake" finishes, or 2-part paints which you post cure. Following proper prep of course.