Painting Aluminum

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

  1. srkowsari
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    srkowsari Junior Member

    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
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    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
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    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
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    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
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    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
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    jonr Senior Member

    I would consider using alodine before the paint.
  7. Thunderhead19
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    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," 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
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    Stumble Senior Member


    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
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    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
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