aluminum boat discoloring issue

[gabagoo]

I am posting 3 pics...the first is a boat we just finished for the Ministry of the Environment and even though you see this strange discoloring in the pic it was not as bad as the next 2 pics which I am working on now.

I thought it was just tar or rubber from rubbing up against a dock, but the boat is new!!

I cant seem to get this stuff off...even tried a little laquer thinner but it seems to be in the finish. I suppose I can stripe it up right over it, but this boat is brand new. How can they sell it like that? Oh right government!!! forgot.

In any case any ideas how this stuff is removed and using what?

 

[letterman7]

Raw aluminum will discolor like that. Greasy handprints will also show, that's what it looks like in the last photo. It is in the aluminum since aluminum is somewhat porous, you can try a little acetone to see if some of it will come out or even Bon Ami (though the finish will show the scratches). The only other thing you can do is polish the entire boat... not something they'll want to pay for, I'm sure.

 

[kanvas]

Zep makes an Aluminum Cleaner called Zep-a-lume. It does a good job cleaning aluminum tubing. I would keep it away from any vinyl graphics. Do a small test section first.

 

[gabagoo]

I called the mfg and it seems short of compounding the boat it wont come off...so to hell with it, I am running the reflective right over it.

 

[rdmdarr]

call your local pontoon boat dealer, they have some stuff that cleans the logs on pontoon boats.

 

[gabagoo]

even after cleaning the work area on this boat, getting masking tape to stick is near impossible...switched to duct tape and even that keeps sliding around......

 

[John Butto]

You are going to have to find a cleaner with acid in it to "etch" the aluminum to clean it.

 

[knucklehead]

Eastwood has aluminum prep wash that works pretty good. I use it on aluminum panels before I grind, and paint them.

 

[letterman7]

even after cleaning the work area on this boat, getting masking tape to stick is near impossible...switched to duct tape and even that keeps sliding around......

Yep. It's the oil they use in the manufacturing that's embedded into the aluminum. It's used to keep the alloy from sticking when it's rolled into the coils. Lacquer thinner just spreads it around - you have to degrease the metal (Simple Green works great here), then hit it with acetone. If you run a white paper towel or cloth over the area and still pick up black, it's not clean. PITA, I know... did that for years at a boat dealership!

 

[signage]

Watch using Simple Green because some versions of Simple Green will cause the Aluminum to Oxidize.