Painting Aluminum

Discussion in 'Materials' started by srkowsari, Jun 26, 2011.

  1. srkowsari
    Joined: May 2010
    Posts: 9
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Iran

    srkowsari Junior Member

    Hi.
    I've designed a 15ft aluminum boat. I'm going to build it this summer but I have a big question about painting my boat so I searched and found some methods like "Anodizing" and "Chromate conversion coating".
    Are these methods a property of aluminum plate that I will buy or a process that I should do?
    If I should do this, it should be before cutting, forming and welding or after these? :confused:

    excuse me for my elementary questions. I'm a novice in boat building
     
  2. gonzo
    Joined: Aug 2002
    Posts: 13,777
    Likes: 435, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    You first need to acid wash and rinse with water to take the oxidation off. Then you lightly spray with zinc chromate. Spray primer and paint after. All the welding and grinding have to be done before.
     
  3. Ad Hoc
    Joined: Oct 2008
    Posts: 6,209
    Likes: 416, Points: 83, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Firstly, you need to degrease. Best to degrease with detergents, solvents are considered too light in that sense. Then you have 3 ways of surface cleaning, 1) etching, 2) cleaning with an abrasive jet or 3) disk grinding. Then the primer and finally the painting.
     
  4. srkowsari
    Joined: May 2010
    Posts: 9
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Iran

    srkowsari Junior Member

    Thanks for your answers.
    Is it possible to anodize the plates before building? It seems to be less troublesome compare to doing this to a bulky boat
    Are these processes something that I can do my self?
     
  5. keysdisease
    Joined: Mar 2006
    Posts: 794
    Likes: 43, Points: 28, Legacy Rep: 324
    Location: South Florida USA

    keysdisease Senior Member

    Choose the paint you want to use and follow their recommendations for painting aluminum. Follow the instructions to the letter, aluminum is not very forgiving to paint shortcuts. If you want a good finish use a 2 part urethane like awlgrip or imron or sterling.
     
  6. jonr
    Joined: Sep 2008
    Posts: 721
    Likes: 11, Points: 0, Legacy Rep: 57
    Location: Great Lakes

    jonr Senior Member

    I would consider using alodine before the paint.
     
  7. Thunderhead19
    Joined: Sep 2003
    Posts: 506
    Likes: 3, Points: 0, Legacy Rep: 21
    Location: British Columbia, Canada

    Thunderhead19 Senior Member

    Why paint? It's aluminum, If you leave it exposed, it will never corrode away. If the boat is for your enjoyment, then save yourself the headache.
    Some trivia
    I was talking to a metalurgist a few years ago about painting aluminum, and I described the process of acid washing the hull as "taking the oxide layer off". He shook his head and said," No....no...the oxide layer forms instantly." He then lectured me.
    The upshot of it was that the acid wash takes off the (I hope I get this the right way around) existing, closed-pore oxidation and permits it to be replaced with an open-pore oxide layer (which the paint can adhere to). Actually sanding and brush-off blasting have the same outcome as acid washing, and they give you a surface profile to enhance the coating adhesion.
     
    1 person likes this.
  8. Stumble
    Joined: Oct 2008
    Posts: 1,896
    Likes: 71, Points: 48, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    Thunderhead,

    Just to add on. As I understand it the speed of aluminiumoxidation is so fast that it is almost instantaneous in a real world setting. It is possible to clean aluminum without this, but it takes working in a zero oxygen environment which is obviously not reasonable for boat building. However once the initial layer oxidizes it acts as a barrier to more oxidation on the substrate.
     

  9. srkowsari
    Joined: May 2010
    Posts: 9
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Iran

    srkowsari Junior Member

    Thanks for your replies on my question. I want to participate in jetsprint racing in Australia so we should paint it. This is our first time that we build a boat and that is why I have so many questions
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.