Removing paint/repainting aluminum?

Discussion in 'Metal Boat Building' started by mosk22rte, Mar 1, 2009.

  1. mosk22rte
    Joined: Feb 2009
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    mosk22rte Junior Member

    If you've seen my other previous threads, you know I'm "restoring" a 12' Klamath aluminum V boat. It's a small fishing boat that I only expect to use in freshwater. Really, what I'm doing is more like "fixing it up" than a true restore.

    Yesterday, I finished removing the rest of the rotted plywood bench seats and the styrofoam, so the hull is essentially stripped down to its skeleton.

    Today, I pressure washed the hull. What's left are the remains of the factory paint job and a second crappy spray paint job applied by a previous owner.

    Today's question: can I do a decent job in my driveway removing the rest of the old paint and creating an acceptable surface for some new paint? From my reading, it seems that there's a lot of science to properly removing paint from aluminum and prepping the surface for a new coat, and while I want to do a good job, I don't want to make this my life's work; this is a fishing boat, not the ceiling of the Sistine Chapel.

    I understand that without proper surface prep a new coat of paint won't adhere properly, and without removing the old coats I'm not going to get a better result than the previous owner. I'm sort of interested in hearing how others have handled this dilemma.

    Finally, has anyone taken a small aluminum boat to a body shop or similar, to have it media blasted and primed? Not sure how much such that would cost, but I hate painting and prep work, so having it done professionally is somewhat appealing.


  2. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    Sorry Jeff, there are no shortcuts to doing the job properly.

    However, the use of sandpaper and water based acrylics will make the boat look pretty again and the cost will be minimal. Try to use a vinyl etch or zinc chromate on the raw alloy before painting.

    There is no way ypou can do the job correctly and not overcapitalise the boat, blasting tin plate is usually out of the question for both costs and practicality (too thin).

    Go with the acrylic gloss house paint mate, it will look presentable, cost minimal, and get the bloody thing back to the water asap.

    I can go on and on about how to do the job correctly, but the cost will be absurd, even doing everything yourself.
  3. drmiller100
    Joined: Feb 2009
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    drmiller100 Junior Member

    any automotive paint store will have "airplane paint removal" chemical.

    spray it on, wait a few minutes, wipe it off, then hose it all down.
  4. Lt. Holden
    Joined: Sep 2007
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    Location: Western Massachusetts

    Lt. Holden Senior Member

    I think DR is on the right track. And since your boat is welded, if you should have any need to sand, ther are no pesky rivets in the way. Do you have any spray equipment? You will need "self-etching" primer to prime the bare metal and it is much cheaper by the quart than in aerosol cans. If the acrylic house paint will adhere properly that is the most economical route, aluminum "auto body" paint is very expensive for what you are trying to accomplish.
  5. mosk22rte
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    mosk22rte Junior Member

    Thanks, guys. Didn't think there was a shortcut, per se, just trying to find the best way to do this given my situation.

    Hmmm...I have a decent air compressor but no spray gun, though the cheaper ones aren't too expensive, IIRC. Not sure how much skill I'd need to use one, but I assume what I'm trying to do isn't too hard. Still, I may need to call around to some friends and see if I can call in a favor or two.

    Any other tips/suggestions? The ones offered so far are helpful.

  6. Lt. Holden
    Joined: Sep 2007
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    Lt. Holden Senior Member

    A good, inexpensive, HVLP (high volume low pressure) spray gun I have used for 6 years is a Porter-Cable that I paid around $70 for; I' ll check on the model number. Spray painting isn't difficult, read the paint mfr.'s instructions carefully and adjust your settings on a piece of cardboard; note that you may have to alter the settings on vertical surfaces to avoid runs.
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Rent a soda ash blaster and remove the paint without harming the aluminum. A good washing afterward and you're ready for paint prep.
  8. Red Dog
    Joined: Feb 2009
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    Location: Australia

    Red Dog New Member

    Hi Jeff

    I had my aluminium power catamarans painted and it became "like new".

    I took it to the local sand blaster $400, then straight to the paint shop done with 2 pack paint ... bit expensive but the boat is valued now at $35k compared with $20K before.

    It is a big boat but with aluminium you can rejuvinate them relatively easily.

    Prices are obviously Australian, but if your hull is sound, it may be worth the effort.

  9. LadyT-Bird
    Joined: May 2009
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    Location: North Carolina

    LadyT-Bird New Member

    I am a 59 yr. old woman. Last week I bought a 14 ft. aluminum boat that had several old chipping paint jobs on it. I went to Home Depot and got 2 cans of Klean Strip (8.99 ea.) Look for the ones that have the free spray bottles attached. Sprayed on sides, and brushed on area under lip. Waited the 15 min. suggested, then used my power washer to rinse off paint. I was amazed. It took paint off to the bare aluminum. The only problem I encountered, under some of the layers there were plastic #'s stuck on. I used razor to remove these, and sprayed these spots again. Power washed and ALL paint was gone. Then I used Simple Green straight out of the bottle and washed the boat. Then power washed again. My boat looks like a new aluminum boat. I think I will use an aluminum polish and leave it as is. It really took the paint off. Good Luck
  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    If you really want to make the aluminum look good, take a buffer to it. You can get a near mirror finish if you so desire, with just elbow grease (okay buffer grease). Conversely, you could take it to an automotive detail shop (where they buff up cars) had have them do it. Buffing does require some skill, some chemicals and of course a buffer. If the aluminum is left to the elements, it will oxidize, develop a chalky coating and get quite dull and change color, quite a bit. Buffed and well maintained wax will prevent this. You could also clear coat the aluminum once you get it looking good.
  11. Brent Swain
    Joined: Mar 2002
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    Brent Swain Member

    A friend, who worked on aluminium boats all his life, including America's cup boats, said he found the only reliable way to get paint to stick to aluminium was a light sandblasting. He tried "Etch " primer on his own boat and found it softer than than the epoxy he put over it. He said the epoxy over sandblasted decks worked much better.
  12. fasteddy106
    Joined: Apr 2009
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    fasteddy106 Junior Member

    Make sure you stay away from anything with steel in it to remove the paint. It will embed in the aluminum and screw up your topcoat. You can get a two part epoxy from any marine supply house once you clean off the old paint and wash it properly. Be sure to stay with aluminum specific prep cleaners and primers. For a top coat use the real stuff, the difference in price isn't worth doing the job twice, get a marine paint suitable for your needs. For howto, you can go to Jamestown Distributors web site, be sure to put aside some time though, the amount of info there can be obsessing for anyone interested in DYI projects.
  13. mudman
    Joined: Mar 2007
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    mudman Junior Member

    I can't believe no one has mentioned Alum-brite. Strip the paint with a paint stripper and then ALUM-BRITE before paint. Puts a nice profile on the aluminum. Very corrosive.

    Trick is to not let the Alum-brite dry. Just put it on there and wait a few minuites, and then pressure wash it off. The paint will stick to the profile very very well.
  14. MikeJohns
    Joined: Aug 2004
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    MikeJohns Senior Member

    Sodium hydroxide (NaOH), also known as lye and caustic soda cleans end surface etches aluminium very well. Most of the commercial products are just NaOH with a brand name. Dissolve the caustic soda into water and paint brush on. Wash with water to stop the etching.

  15. stextor
    Joined: May 2009
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    stextor New Member

    Your decision and results

    mosk22rte, Your post summed up nicely the work I am now tasked with. May I ask a few followup questions?

    1 What were the methods you decided on to remove the paint, prime it and paint it? Mentioning brand names are good with me:)

    2. How did it turn out?

    3. Any tricks? Lessons learned? What was the most difficult part?

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