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Paint bubbling on 2004 Prius: What to do?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Eug, Jun 14, 2011.

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  1. WE0H

    WE0H Senior Member

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    Sorry didn't read the whole thread. Just clean it up as much as you like and spot repair the paint. Other option is a good junkyard hood in the same color :)

    Mike
     
    #21 WE0H, Jun 15, 2011
  2. Eug

    Eug Swollen Member

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    Sorry it took so long... but better late than never I guess. Here is the picture of the underside. Interestingly, it's near where a round hold in the metal exists on the underside.

    BTW, I also started noticing this on a wheel, and have also included a picture of that too.

    Based on your comment, I decided to do nothing. If the issue is purely cosmetic, I can live with it.

    P.S. Since I don't have a garage anymore (since I moved to a new house in 2007), the car stays outside 24/7, including during our winters. Once thing I've noticed is that after a good rain, my brakes sometimes sound squeaky until I use them a bit, presumably to scrape off the rust that has accumulated on them.
     

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    #22 Eug, Apr 14, 2012
  3. edthefox5

    edthefox5 Senior Member

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    Doesn't matter if its aluminum. Paint got a pin hole in it and water got under it. If you pull that spot off you'll see very little corrosion on the metal. Its all in the paint.

    I wouldn't worry about it like you said. The real horror show is underneath the car. Ever lay under the car and look at the suspension front & back? Oh the humanity!
     
    #23 edthefox5, Apr 15, 2012
  4. Eug

    Eug Swollen Member

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    Yeah, it's a year later now and more of the paint has bubbled off. There is very little corrosion though. I'll get some more spot paint, because my old one is all dried up.
     
    #24 Eug, May 1, 2013
  5. Mike500

    Mike500 Senior Member

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    The alloy used for the hood is quite corrosion resistant. It is probably 5032 aluminum magnesium alloy like that uses on the tops of soda cans and road signs. It is NOT the aluminum that has corroded, it is the paint and primer that has given up its grip.

    Most aircraft are made of a much less corrosion resistant alloy, mainly 2024, which has a high percentage of copper.

    Painting aluminum is challenging for most novices. It needs to be etched with chromic acid or phosphoric acid. Hexavalent chromium paints like zinc chromate primer were widely used from the 1920's until the late 1980's. They are no longer widely available since hexavalent chromium is a toxic carcinogen. Remember Erin Brochovich?


    Phosphoric acid is available as a "paint prep" solution at Home Depot or Lowes.

    Rustoleum sells a widely available "self-etching" spray can primer, but it lays on too thick.


    For painting aluminum, I have personally switched to "phosphoric acid bath etching" and a direct to metal epoxy paint. The stuff dries very slowly unless oven baked. Aircraft manufacturers have also switched to the epoxy. They use infrared baking.
     
    #25 Mike500, May 1, 2013
  6. Eug

    Eug Swollen Member

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    Thanks. I learned a few new things today.

    However, wouldn't paint colour matching be very hard with 3rd party paints? And are you suggesting I need to do phosphoric acid etching even for just spot patching with Toyota spot paint pens?
     
    #26 Eug, May 1, 2013
  7. Mike500

    Mike500 Senior Member

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    Yes, the etching is necessary with aluminum, otherwise, the paint will not stick.

    I've heard that lemon juice or vinegar has also been used. But, I have not tried them, since I have access to phosphoric acid.

    You should also rub off the oxide layer with an abrasive pen. 3M has them, and they can be had at Walmart.
     
    #27 Mike500, May 1, 2013
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