Acid Dip versus Media Blast for resto?

Discussion in '40- & 55-Series Tech' started by dieselcruiserhead, May 30, 2006.

  1. dieselcruiserhead

    dieselcruiserhead

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    anyone have any experience with acid dipping a car for a resto before? No one in town seems to do it for automotive purposes, mostly galvanizers, but the two I talked to are both willing to do it fairly cheaply (hot dip a whole FJ55). This will basically boil any and all rust out of it. Drawbacks are 1) it will leave a residue that will be hard to get off, 2) it will need to be primed very quickly otherwise it will flash rust, 3) it will literally remove paint and everything in all places, all the nooks and crannies etc, so anywhere that I cannot paint will rust... and 4) these guys don't have a whole lot of experience hot dipping a car body before. Otherwise I have a good bid on media blasting the body to bare metal for $500 which I am also considering... Any comments or ideas on this?
     
  2. dustin

    dustin

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    I am thinking of doing the same thing at a place near my house. I will be doing my 40 tub and parts though- smaller.
    You list the concerns I know of- getting paint back into the areas that got eatten out. In some places, you may end up eating out holes- which can be viewed good and bad- good cause atleast you found the prob that was going to find you. Both you have to get primer on right away. there may be less prep after the dip. not sure. But, I like the idea of the dip for doors, hood, etc. Plus, unless they drop your stuff, theres alot less likelyhood of it getting dented. Blasting can warp body panels if done impropperly.

    -dustin
     
  3. F-junker

    F-junker

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    I would think a mediablast would be a better method, no residue, and minimal damage to the metal; media blasting can remove paint and primer one layer at a time.
     
  4. CruisinGA

    CruisinGA

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    media blast anything that has nooks/crannies that cannot be accessed to coat
     
  5. Brian in Oregon

    Brian in Oregon

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    I don't like dipping ANY parts that have seams, because it is nearly impossible to neutralize the stripping agent once it penetrates inside. Later it capillaries out and ruins the paint job. Sometimes you get lucky and this doesn't happen. Sometimes this happens right away, and sometimes in a coouple of years or more. It depends on the seam, corrosion in the seam, pentetration of the agent, how well it got rinsed out, humidity, how well the primer and paint sealed it, etc. Sometimes everything is done exactly by the book and it still capillaries out, looking like rust bubbles with whitish "battery acid" fingers.<br>
    <br>
    For parts without seams that can be thoroughly rinsed, it's fine.<br>
    <br>
    Now, if you have something with a lot of rust that needs to be eaten away, you may have no choice. Discuss with them putting the item in a neutralizing bath twice and making sure it is very well rinsed. Make sure the part is completely dry before painting - by this I mean make sure the inside of the seams have had time to dry and have warmed up enough. This is a job best done in the summer or artifically by turning a fuel fired space heater on it. Make sure water never gets into the seams in the future.
     
  6. gladly

    gladly User title SILVER Star

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    a friend of mine back east is restorinng an old landrover dormobile, has acid dipped and galvanized almost every steel part on the thing. I wonder if you'd be able to just galvanize the whole body? might be worth looking into, apparently it is cheaper than you'd think to galvanize stuff.
     
  7. UNO_RACING

    UNO_RACING

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    It really depends on how bad the cancer is. I would suggest getting it media blasted. I just got back my frame from a blaster that used a glass compound of sorts. The frame came out great couldn't be happier for the $200 that was spent.

    Also, the blaster had a hell of a time blasting my FJ frame becasue the previous owner used POR and it was a PITA to take off. Wouldn't you guess under the POR there was still surface rust. Rather than spend the money on POR I used an industrial undercoating. The frame looks cherry.

    Interesting thing is that all the bump stops and rubber break lines looked new too!

    Alternatively you can purchase AIRCRAFT stripper and go to town. THat stuff is way powerful! I used it on the hood and it took the paint off down to the metal with no problems whatsoever.

    Considering the inexperience of your guys, go with the media blast. It works great.

    Later,

    UNO.
     
  8. bsevans

    bsevans Focus on the Journey

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    Acid Etch & POR-15

    POR-15 chemically bonds to rust and prevents moisture from reaching the metal under a properly applied process. It does not make rust go away, disappear, or turn into something else. The fact that it was a PITA shows how well the product bonds to a steel surface that has oxidized.
    I would advise against a acid etch process. Where I worked we tried the process followed by flushing and then a galvanizing. After the surfaces had been galvanized the entire steel structure was painted to mil-spec requirements. The steel optical layout tables were inside a lab with a controlled environment. Within 3 years the acid etch that was never fully flushed from the welded crevices started to form a white oxide ash at many of the seams. Right through the plating and paint in a controlled environment.
     
    Last edited: May 31, 2006
  9. dieselcruiserhead

    dieselcruiserhead

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    cool guys I think I will go with the blast.. Appreciated..
     

  10. my64fj40

    my64fj40

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    And then have it powdercoat primed...


    The electrical charge does a good job of pulling the powder into those hard to reach areas


    Plus you never have to worry about it rusting




    -my64fj40
     
  11. 4x4Poet

    4x4Poet

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    That's interesting. I don't want to powder coat a frame I'm currently stripping of componets because I understand that powdercoatings run soft on paint/coatings hardness scales which makes them vulnerable to gravel strikes. Also, fixing scraps would prove problematic compared to touching up paint/POR15/etc. Most advice I've received recommends frame powdercoating only for show cars or fair weather drivers.

    But just having the powdercoating primer step done would allow for a *hard* topcoat over, as you say, more thorough electrostatically applied primer coverage. Reduces powdercoat costs, too, by skipping the powder *topcoat* that would require a second application/curing process. One stop blasting & coating, too. Touch up would be as easy as the separate topcoat (paint/POR15/etc.) calls for. I could spray or brush on POR15 or some other high solids topcoat.

    Thanks for the tip. :beer:
     
  12. bsevans

    bsevans Focus on the Journey

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    Powder coating does not require a primer. After media blasting, the item needs to be handled with gloves so no oil or sweat gets on the surface. I've been powder coating hardware at work and on my cruiser for close to 20 years and I've never had a conversation with a powder coat house that talked of a powder coat primer as a first step process. I do not recommend it for a cruiser frame. It will not give you complete coverage on the inside surfaces. You also will not get good coverage of sharp inside corners due to the way the charged metal tends to cancel itself at sharp inner corners. You will get coverage but it will not be as thick as the rest of the frame. Powder coating will only stick to clean metal. POR-15 with a UV top coat will do a superior job. With their cotton ball wire handle applicators you can get complete inner frame coverage.
     
  13. fatmoe

    fatmoe

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    Alternative type of media blasting

    Found this article the other day and have been wondering how well it would work for a rusty old tub like mine, less damage to the material, but still removing all the rust and gunk. Looks intriguing, but don't know about availability, but they are in Utah which may work for you Diesel.

    http://deseretnews.com/dn/view/0,1249,635211664,00.html
     
  14. Soul_Man

    Soul_Man

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    I had my frame and body parts dipped. Haven't painted yet (except the frame) so I can't comment on it leaching out under the paint. The strippers dipped it all in a rust preventative after stripping/washing and about 4 months later I don't really have any flash rust or anything (stored indoors, of course).

    I do have some concerns about hidden areas. For instance, I am planning on removing the skin from the windshield frame (need to anyway for repairs of rusted metal) so I will be able to paint the inside of the frame before I re-skin it.

    I got my frame hot-dip galvanized. Best way, IMHO to get every nook and cranny protected. I then painted using an undercoat gun that has angled wands (can get from Eastwoodco.com) to get all the boxed in sections with paint (DuPont Imron).

    Blasting will never get inside the boxed parts of the frame. Even with 90 degree tips on the undercoat gun, it was hard getting all the areas painted.

    You can't galvanize the body as the heat will warp the sheetmetal. I tried real hard to get my body dipped, but every one I spoke to and everything I read said you run a significant risk of warping all the panels.
     
  15. dieselcruiserhead

    dieselcruiserhead

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    cool thanks for the info. .. Also thanks for the lead on the dry ice blasting. Seems way cool but I called and they said sandblasting is probably better and cheaper cause they can't bring it down to bare metal easily supposedly. Bummer, but cool! Looks like I am about $500 for a complete blasting job inside and out as far as I can tell.. Andre
     
  16. CruisinGA

    CruisinGA

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    My cruiser had the underside sprayed with 4 coats of epoxy primer and 2 coats of chassis black topcoat before I got it. (PO had an industrial coatings buisness)

    Very tough, bonds well, looks like the underside of a car should.
     
  17. niblik

    niblik

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    definitely media blastin!

    i'm currently tearing apart the final bits off one of my 40 tubs to get blasted and coated with a durepox substance.. tough as nails.. will do my chassis too..
    doin the media blast thing mainly cos of speed of job and price..

    drop it in...
    1 day later pick it up....

    easy! tub will cost about $400 worst case scenario.. depending on grease etc..

    good luck with the restore, post some pics too.. its good to see 40's are popular as ever! :bounce: :bounce2: :D
     
  18. Degnol

    Degnol

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    Just as a point of clarification, I think it is a caustic dip that they use to chemically strip metal. Like lye. And my personal vote is for blasting.


    GL

    Ed
     
  19. 4x4Poet

    4x4Poet

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    Yup, I'm with ya all the way.

    First, the powdercoating *houses* here that I've talked to do powdercoat as a one step process, but they offer a zinc-based *primer* powdercoat application for extra rust protection. They recommend, but don't demand, zinc primer up here on exposed metal like frames, axles, etc since snow, road applied icemelt, and gravel roads abound. Actually, they don't recommend powdercoating driver rig frames or axles if you ask, but they will do as the customer pays.
    After applying the zinc primer, they apply the usual powdercoat over the primer. Adds cost to apply and cure twice. As I mentioned above, I'll instead take the primer coated frame and topcoat it myself with something superior to powdercoat for hardness. More below.
    Second, I didn't mean to imply that any primer was required for powdercoating to stick. Also, the powdercoating folks 'round here can blast sand outdoors with no enviro concerns, so any frame I give them will be cleaned by them after I remove grease, undercoat, caked on dirt, etc. And I happen to be working on an old Chevy truck C-channel "ladder" frame, which doesn't have any boxed sections. Sorry I didn't make that clear.
    Good points on your part concerning getting boxed sections rust free and well coated inside the sections. I share your *philosophy* for Cruiser frames. On this unboxed Chevy frame, I intend to topcoat the primer powdercoat with POR15 and/or another high solids coating. Whatever's left on top will provide UV protection.

    Could you expand on how "charged metal tends to cancel itself at sharp inner corners". I haven't heard of that one. Is that just inside boxed sections or any sharp corners?

    Are those "cotton ball wire handle applicators" these DAUBERKITS? I didn't know POR15 offered those. I only found them after searching after reading your recommendation. Another great tip on this thread. Thanks. :beer:

    All in all, you gave some great advice. My fault that it didn't all apply to my situation. I was concentrating on the tip my64fj40 gave rather than the specifics of my situation. :whoops:
     
  20. bsevans

    bsevans Focus on the Journey

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    Poor Coverage in internal corners

    On sharp inside corners the surfaces that make up the joint have in most every case a larger surface area and tend to starve the joint of receiving the same quantity of powder. The powder will tend to spread itself on external features (flat plates, external corners, bends) due to the fact that the surfaces are not competing for the powder like an internal corner. The charge on the metal radiates out from the surface to attract the powder. Two, three or four plates that can make up an internal corner will offer a much greater attraction. It is similar to water finding the path of least resistance.
    The roof rack on my FJ40 had to have two heavy coats laid on to meet my requirements. The only reason I got them to do it was the fact that I have brought them so much business and they have taken a lot of pride in being responsible for all the powder coating on the exterior, interior and under the hood of my vehicle. And yes, it pays to develop a relationship with companies you use. If I had paid the going rate for powder coating, especially the type of powder coat I use (Cardinal Black Hammer), I would be in the poor house. People are always commenting on the texture and shine of the powder coated items on the vehicle and I know where to send them.
     
    Last edited: Jun 2, 2006

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