Alu - salt water corrosion

[LadyInBed]

What is the easiest way to neutralize cast aluminium before painting ?
Would zinc spray paint be any good as the primer layer?

Background - I am referbing a manual bilge pump and the lower bowl / cover sits in a residue of water which over time has penetrated under the factory paint.

 

[TradewindSailor]

I'd be tempted to clean all the paint off and treat it with Alumiprep http://www.gcmdistributor.com/files/AWLGRIP PRODUCTS.pdf
or another phosphoric acid based cleaner. I would keep it bare and perhaps coat it with an oil based protectant like Aluma Guard by Rupp which is used for all the bare aluminium (non-anodised) bimini and targa bar framework on my boat.

If you were to paint it, the zinc primer would probably be good over the phosphoric acid prepped surface .... or you could use a primer like Primacon (International), but unless it is properly prepped with the phosphoric acid nothing will stick.

 

[LadyInBed]

Thanks for that, I've just noticed the Aluminium Pitting thread. Oops!