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How to keep a raw aluminum outer hull looking good?

Posted: Thu Aug 02, 2012 8:22 pm
by cbrammer
I'm getting a lot of discoloration --burnt/ blue discoloration on and below the water line of my aluminum hull (from being in the water). Would wiping the outer hull with Allodyne help to keep the discoloration from happening? Or what can I do to keep the clean aluminum look?

Re: How to keep a raw aluminum outer hull looking good?

Posted: Thu Aug 02, 2012 8:55 pm
by mcmbuilder
You may want to email Kevin, he is pretty sharp on this type of stuff. I personally have never had any experience with anything other than painting the hull that will keep it from becoming discolored. What I did to keep it looking good was to use a white 3M pad with a real sudsy soap and clean it. But I don't know of anything you can put on the boat to keep the discoloration from occurring.

Re: How to keep a raw aluminum outer hull looking good?

Posted: Fri Aug 03, 2012 5:14 am
by jcallends
Not famillar with Allodyne but for aluminum floats on pontoon boats muratic acid (hydrochloric) is used. Bad stuff to work with, need long rubber gloves and a face shield while useing. Also the cleaning is done from the bottom up or you will get etched streaks in the metal.

Re: How to keep a raw aluminum outer hull looking good?

Posted: Sat Aug 04, 2012 11:36 am
by Kevin Morin
Charles, the bare metal will discolor from dozens of trace compounds in salt and fresh water. This is an interaction with the aluminum oxide and the trace chemicals, many naturally occurring in water not necessarily man made, that leaves a refraction or patina to the aluminum oxide. Lots of colors, blueish grey or gunmetal colors are common.

You can remove the oxide layer using Zep-a-Lume, or Alum-a-brite (not sure of exact spellings) which are acid mixtures. I think you've already used one product to etch the boat? so this won't be news to you.

For the sake of safety lets make sure we mention PPE.
As mentioned these mixtures/compounds are not for the casual user, I wear full rain gear, glasses AND face shield, inside disposable gloves over elbow length 'parts washer' gloves and rubber boots. If I spray the acid onto the boat, I wear a rubber half face (North or equivalent) air purifying respirator with the organic vapor cartridges to avoid breathing any acid misted into the air.

These compounds will clean the boat, but the cause is not going away. If you would like to paint the boat and leave it natural, then look into POR V15 Glisten; Evercoat's products; VHT Clearcoat, or http://www.nyalic.com/ all these products will keep the oxide intact for longer but none of them will last forever.

You can keep the boat looking 'new' by regular etching but I'm not aware of any way to keep the oxide from colorizing or getting a patina except by coating or regular removal.

cheers,
Kevin Morin
Kenai, AK

Re: How to keep a raw aluminum outer hull looking good?

Posted: Sat Aug 04, 2012 2:22 pm
by mcmbuilder
See, I told you he is very sharp on this kind of stuff.

Re: How to keep a raw aluminum outer hull looking good?

Posted: Mon Aug 06, 2012 1:37 pm
by cbrammer
Thank you for your help in understanding this Kevin. I've got enough time in on this that I don’t think I will be welding on it any more so --- it’s time to think paint! I'm not looking forward to stripping all the hardware and wiring off that’s in the way (or the motor).