Painting Aluminum Questions

mcattac

Seaman Apprentice
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Jul 25, 2007
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38
I have spent a bunch of time here searching threads for aluminum painting info. I found a lot of it and forgive me please if I ask a question that has been answered 1000 times.

I'm going to repaint my 18' Starcraft project boat.

Some of the bare metal is exposed and some of the paint still exists.

I understand that using a zinc chromate etching primer is preferred on unpainted raw aluminum and I will try to do this. My question is in regard to what happens if this primer contacts some of the existing paint?

Will it bubble the old paint or will it simply cover over it?

I want to clean up the old paint and rough it up with 150-200 grit paper. I will then wash it thoroughly and use this as the base for my new paint. But for the areas of raw aluminum here and there where I patched old holes with the MIG and ground them smooth, I wanted to use the zinc chromate. But I'm afraid it will lift and bubble the old paint like stripper does.

Anyone have any experience here?

Last question - what kind of paint should I use.

I have read of some guys using Rustoleum. I went to their website and it specifically says Rustoleum is not recommended for applications below the water line???????

Function here is more important to me than form.

I don't want it to look like crap, but I want a coating that will hold up well.

Any suggestions here???

BTW, I will be rolling the paint on and flipping the boat to do this. I don't have a compressor and sprayer.

Thanks for the help.

Mac
 

CheapboatKev

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Oct 4, 2008
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5,813
Re: Painting Aluminum Questions

Thats a great question of the zinc chromate on existing paint..I dont know the answer for you.
If you saw my thread, I used rustoleum.
I believe you dont want to use rustoleum below the waterline on a boat that stays IN the water. I feel it is fine for a trailer queen:D

Lets see some pics, do ya have a resto thread going yet?
 

mcattac

Seaman Apprentice
Joined
Jul 25, 2007
Messages
38
Re: Painting Aluminum Questions

Thats a great question of the zinc chromate on existing paint..I dont know the answer for you.
If you saw my thread, I used rustoleum.
I believe you dont want to use rustoleum below the waterline on a boat that stays IN the water. I feel it is fine for a trailer queen:D

Lets see some pics, do ya have a resto thread going yet?


I have some pics and stuff I posted months back elsewhere in the resto area I think. My plans are to post it all when I finish this boat. I started it almost 2 years ago. I have filled all the holes in the hull from past antennas, cleats, lights, pole holders, railings, everything! I will be drilling all new holes when the time comes. I have also increased the transom height to accommodate a 25" long outboard to keep rough water from splashing over the transom. Also retrofitting right now with a belly fuel tank. Like I said.........I will post things in great detail when it is finished. But this project won't be done for at least another year or more. Sorry!

Anyway..........

I may want to keep it in the water sometime in the future - not sure.
So I really want to go with the right paint.
Like I said, I'm more concerned with what works, not with what looks pretty.
I'll use a 2-part epoxy or spray with Rhino bed liner if that's the way to go.

Seriously, I am looking for maybe a grey paint that is very durable and withstands the rigors of heavy fishing in salt and fresh water.

Thanks.
Mac
 

Rickairmedic

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Apr 24, 2009
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Re: Painting Aluminum Questions

Mac a look at Northbeaches resto thread will answer your question . he used the Zinc on his painted and bare aluminum and it worked out great and so far no bubble and no peling paint ( other than where he ripped the bow cleat off ) and that had nothing to do with the primer :D. I will add from what I have read and understand you should use a Bottom Kote Marine type paint if you are going to be leaving it in the water more than 24 hours.


Rick
 

reelfishin

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Mar 19, 2007
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Re: Painting Aluminum Questions

I just got done repainting a smaller Starcraft, the boat had a combination of old original paint along with some newer paint. The self etching zinc chromate primer attacked the newer paint, but didn't bother the original paint too bad. It did wrinkle the sanded edges in a few spots where the original paint was but nothing that I couldn't sand out and reshoot.

The whole idea of the self etching primer is for it to gain a real grip on the surface. It's pretty tough stuff to remove as well. It sort of stains the metal.
(I use self etching primer on both glass and aluminum. I also like having a uniform color base coat when the final coat is a lighter color too.
 

Andy in NY

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Oct 25, 2007
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2,109
Re: Painting Aluminum Questions

I spot primed mine with zinc chromate... no issues where it went over existing paint so far... been about 2 weeks.
 

geedubcpa

Petty Officer 1st Class
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Jun 1, 2009
Messages
209
Re: Painting Aluminum Questions

Almost all paint says not to use below the waterline - if you are keeping your boat on a trailer - no problem, this is only a problem when the boats sits in the water year around. I have been involved with 3 marine painting projects and never had a problem with the paint because the boats are only in the water during use.

I used RUST SCAT from coronodo paints with very good results, I sprayed my boat with a HLVP spray gun.

The self etching primer did not hurt my existing paint.
 

erikgreen

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Jan 8, 2007
Messages
3,105
Re: Painting Aluminum Questions

Just a thought, I've seen some of the newer "cold galvanizing" paints that are able to be used as primers. It would give the paint something to hang onto as well as providing extra corrosion protection (as if aluminum needed it).

Erik
 

spadman

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Mar 6, 2009
Messages
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Re: Painting Aluminum Questions

what type of Rustolium do you use on the bottom? i will be able to round out that part of my resto if i knew what paint to use!lol! i am preping my aluminum with a good stripper, then washing it. next i am going to use a "skin brightener" (it is what the AirForce painters use on KC-135's) and then wash that. lastly i am going to use alodine on all metal exposed. i am told that at this point, any etching primer and paint will work. the surface is ready and sealed and the rest is just good protection. i personaly an going to zinc chromate EVERYTHING! i love the aircraft look when i am looking at aluminum. if it is good enough for our GA and military aircraft, it is good enough for me.
i have heard about people using rustolium, but somehow never caught what type and other gritty details about it.
 

Rickairmedic

Commander
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Apr 24, 2009
Messages
2,576
Re: Painting Aluminum Questions

Spadman if your boat will be trailered mostly and not left in the water then regular old rustoleum will work just fine . On the other hand if your going to be in the water for more than 24 hours then you ned a Bottom Kote paint.


Rick
 

North Beach

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Sep 29, 2008
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2,022
Re: Painting Aluminum Questions

My boat had so many small bare spots that I just shot the whole thing with ZC-some over existing paint some over bare metal. I had no problems with it lifting paint. I will add that the paint I went over was the stock 60's stuff.

As far as paint brands go, I think some of it is kinda like ford vs chevy if you know what I mean. I went with pettit because I liked the way the folks talked to me on the phone. The folks at interlux were a little to stiff. You will use this and you will use that-just kind turned me off.

And I should add that at this point, I don't even know if I got good paint. So far it's holding up real well in my air conditioned garage:D
 

spadman

Cadet
Joined
Mar 6, 2009
Messages
16
Re: Painting Aluminum Questions

LOL! just plain ol' rustolium fence post pain heh? after the prep work i have in line, i guess it will work as good as another. i would rather just have a local guy come over and just hand the paint to me or even pour it in my new paint gun. it is just easier that way!!!:D
 
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