Need help on finishing Aluminum project boat
How do I prep raw aluminum for finishing. I've got part of the boat shinny, some appears to be rubbed out, some wheeled, etc. It is a project boat and just looking to get it looking decent.
What's the best type of finish? Leave as is? Paint it?
Looking for ideas here, new to this boat building stuff.
acid etch and alodine
Acid etch and alodine before painting is how we do it in aviation. Not sure where to get it locally other than aviall, it's not cheap, but neither are boats. Rub the acid etch on with scotch bright, then spray it off with the hose. Wait a few minutes or until somewhat dry, then apply alodine with a sprayer (hand sprayer, like the ones windex come in) wait a few minutes and wash off. Color will be slightly gold after this procedure. The alodine puts a oxidization layer on the aluminum surface, preventing further corrosion, then the paint of your choice or budget can be applied.
Try getting in touch with sportdrifter on here. He has the best shine I have ever seen on an aluminum boat and I know he runs it in the salt and fresh water so it does see some use not a trailer queen!
If you want to paint it do a search here www.riverjetmagazine.com one of the forum members (Eastside) recently did a how to series on painting an aluminum boat that was very good!
Good luck with your project!
Any more prep?
Thanks guys! I received it with it partially shiny, untouched and partially rough (what looks to be wheeled or sanded, not sure). Should I have all one or the other before I etch it? Is it okay to use in salt or fresh water with no finish? Or is a clear finish applied first? Sorry, got no experience with this stuff
I will check out the links you left for me Bronco, Thanks!
My dad's a boad builder in Soldotna and I've worked at his shop with him many times. His normal finish for any aluminum product is nothing more than an acid etch using Zep-A-Lume or similar. Using an all plastic pressure sprayer, available from your home gardening centers (Fred Meyer, Home Depot, Lowes...) you just spray a wet coat on the aluminum and let it sit and foam up for a few minutes, then thoroughly rinse it off with water. This will remove the oxidation and leave a bright finish. Naturally the aluminum will oxidize and grey over time, which is not really a bad thing. Aluminum oxide is considerably harder and stronger than the aluminum.
If you're going to put on any type of finish, you'll need to put the alodine on right after the acid bath has been rinsed. This will give you an adhesion layer that is gold in color, but is not typically used as a stand alone finish. On interior surfaces, he does this and sprays on Zolatone with an air sprayer. He rarely paints exteriors except on drift boats, and then only above the water line. Same thing, acid, then alodine, let it dry, then spray on a quality automotive paint.
A completly smooth and polished surface is not the best for getting stuff to stick to aluminum, so you're actually better off with a rough surface. You can get an evenly roughened surface with either a disk sander or a wire wheel, depending on the shape of the surface. If you have grinder marks you want to get rid of, use a disk sander to smooth them out. A final run over with a wire wheel will give you an even scratch pattern. If you're going to do Zolatone on the interior, the rougher the better and you won't be able to see it. If you're going to do paint, then you'll want to get a nice even and fine textured scratch pattern that you can live with if it's visible through the paint.
If you go the sander route, use a medium grit (100) and frequently spray the disk with some Pam cooking spray or similar cheapo variety. This keeps the aluminum chips from sticking to the disk and clogging the grit so easily and will save you a lot of work. To help get an even acid bath, do a soap and water cleaning first to remove the cooking oil residue.
One last tip, if you're going to wire brush the surface, you'll be better off doing an acid etch first. This will remove the hard oxide and allow the brush to get an even bite on the surface. After you're done with the brushing and the pattern looks good, do another acid etch to clean it up and remove any residue before moving on to your finish.
All the chemicals you need are available from your local metal supply yard.
Good luck with your project.
Here are a couple of links that should help you out.
This one is on polishing http://www.riverjetmagazine.com/fuse...&enterthread=y
Here is the one on painting
I have heard of this stuff on this forum and it appears to be good stuff, but a little spendy. I plan to strip my boat next year and treat it.
Man, you guys are making this way too easy for me...well, the research part anyways!
JOAT-That is a fantastic description! Sounds like you've done a few of these boats! I will up some of your advice and may pick your brain later for specifics.
Yes, you can use the aluminum as-is in the salt ...just make sure that your bonding system is in good shape and that you put zincs on the boat as well. You probably have zinc mounts on the transom, right? If any parts of the boat are a) aluminum, and b) separable (not welded or riveted to the hull), then they should have a ground strap installed to connect them to the hull electrically. That'll make sure that your zincs take all the corrosion, not the boat. There's a book called "Metal Corrosion in Boats: The Prevention of Metal Corrosion in Hulls, Engines, Rigging and Fittings" by Nigel Warren that's pretty good ...I've got the book ...well, if my darn brother ever returns it to me that is.