Advice on cleaning aluminum

[Spectre5922]

Hey guys,

I got a used (but REALLY cool) leaning post for my boat.  I am going to recover the seats (it has 2), but need some advice on how to clean the aluminum frame.  I tried barkeeper's friend and a scotch-brite pad, but that is REALLY slow and doesn't get everything.  It has the typical saltwater corrosion/gunk on it.  What do you guys suggest to try and attack it a little faster?  I know there is going to be a lot of elbow grease involved in the later stages of cleaning it up and getting it polished, but after 2 hours yesterday, I barely made a dent.  Is there anything that I can get for my grinder or something that will clean this thing up faster that won't damage the aluminum?

I can't post pics from Photobucket from my work computer, but I'll get a pic of the leaning post up in a few hours.

Thanks for any advice.

[slvrlng]

Depending on the depth of corrosion or marring of the surface I would wet sand it. Always start with a grit that will get the crud off but at the same time not put too big a scratch in it. You will need several grits of sandpaper. I suggest starting with 1500 to see what that does and use 1200 or 1000 on the rougher areas. Once it is all cleaned up go over it again with 2000 grit and if you can find it 2500 grit. Then get some polishing compound of some kind (I like using Presta 1500) to get the small scratches out then I go over the whole thing with Flitz or some other kind of metal polish that helps protect it. This sounds like a lot of work but once you get the initial crud off the rest is just a fast quick sanding. Just make sure and wear surgical gloves or else your hands will have what my fellow Airstream owners call "Aluminitis" (really black hands)          

[Spectre5922]

I don't mind the work at all as long as I get some progress.  That's all this project is right now.  I tried 2000 wet sanding paper and it was not course enough.  I will go by O'Reilley's and pick up some 1000 during lunch.  Here is the pic of the leaning post.  It is cool because the bench seat folds up so I can have a spot to store a cooler under it, then raise the seat to get access to the cooler.  I only paid $150 for it and I thought that was a STEAL!

Also, I'm way ahead of you on the surgical gloves.  I bought 2 boxes of them when I started working on the boat for fiberglassing.

[slvrlng]

Here is a link to a site that specializes in polishing aluminum if you need more info.

http://www.perfectpolish.com/

Edit------ try the 1500 first! Then the 1200 and 1000 as a last resort! The bigger the scratch the harder it is to get out!

[Spectre5922]

Here is a link to a site that specializes in polishing aluminum if you need more info.

http://www.perfectpolish.com/

I just checked out the video.  That is awesome.  Thanks!  I actually saved it in my favorites.

[slvrlng]

I have one of those Cyclo polishers I found at a pawn shop near our local airport. 75 bucks and it is almost like new, the guy didin't know what it was.

[pete]

thats a cool looking leaning post,different design,only problem with sanding tha alum is that you are taking off the anodizing,when you polish it it will look good for a while but the surface of the alum will want to oxidize,you might want to paint it or have it powder coated,good luck!  

[slippery73]

thats a cool looking leaning post,different design,only problem with sanding tha alum is that you are taking off the anodizing,when you polish it it will look good for a while but the surface of the alum will want to oxidize,you might want to paint it or have it powder coated,good luck!  

As Pete said, if your leaning post is anodized its not going to sand or polish like bare aluminum will. You will have to sand all the way through the anodizing otherwise you will see the areas where you burned through the anodization coating to the raw aluminum. The anodization is what protects the aluminum, by removing it your going to have a maintenance nightmare.  We used to use a product called ABC Corrosion buster, you might try that first. Its essentially a gelatinous acid solution that you wipe on. It would still have to be polished from there. I'd try a polishing wheel and some brown stick compound before I tried sanding it.  You'll want something to clean the metal though before you polish it.

You may be better off in the long run to powder coat it or paint it.  I'd opt for paint over powder coat as I've seen many powder coated finished fail in the marine environment.  If you do go with a protective coating you will want to isolate all fastener points with delrin washers, or equivalent so that you don't break the surface of your coating with your screw heads.  The dissimilar metals will corrode much faster as well.

[gran398]

The design is terrific, and agree with you, a super value for what you paid.

And agree with the other posters...once the anodizing is stripped, its gone. Then even when you get it pretty, and wax it, etc...two months later its showing black leeching, spotting etc.

You can sand/finish per direction...then powder coat. The reason I say powder coat is per Gore Brothers Marine Fabricators here in town. They are well-known across the SE, hopefully your way as well. They are now using a preparatory process and production procedure for powder coating which they state eliminates previous issues; internal blistering, improper adhesion, etc.

Am sure Quality in Tampa will also gladly advise on current aluminum coatings/recommendations.

Excellent point on the delrin washers...coating or not.

[CaptSteveBetz]

There is a product on the market called Sharkhide aluminum cleaner. They also make aprotectant for after it is cleaned.
I have not used it but it looks like it works well. I saw them using it on Ship Shape TV to renew the pontooons on a Pontoon boat.
I am going to give it a try on my trailer one of these days when I get around to ordering some.

 www.sharkhide.com

[fitz73222]

It kind of appears that the anodizing is already compromised anyway. I suggest painting with some really good prep. Starting with a good dust mask, start wet sanding with 220 grit to break the surface, followed by 400 grit. Take a fine Nicklson mill basturd file and file a nice smooth radius on every sharp edge; like the the mounting flange edges. Paint hates sharp edges and it will chip or flake off at some point in those areas. Hand sand all the filed areas with the 220/400 process. Buy some aluminum prep wash, which is a very mild alkaline solution to deoxidize the surface. I would use paint designed for outboard lower units. Prime with Zinc Chromate (If you can find it) or zinc phosphate, then  spray a nice outboard white or black. This paint is designed for the marine environment and if you think about it, there isn't a much worse environment that what an outboard gearcase must endure. Tempo makes a good laquer paint, unless you want to use a factory outboard color. Just make sure that the primer and paint are the same brand to ensure compatable chemistries. The absolute key to good paint and primer adhesion is multple light coats instead of a few heavy coats. It will look smokin hot for about $50 worth of materials and last many years with washing and an occasional wax.