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Best water-proof body filler?

Discussion in 'The Hokey Ass Message Board' started by rustyironman, May 8, 2011.

  1. Whats your guys opinion on the best water-proof body filler? I will be using it to fill some small imperfections in some welds and body work, so I really don't need chopped fiberglass in it like most the waterproof fillers. Don't want to use the regular stuff as I don't want it wicking moisture from the back side.
  2. darkk
    Joined: Sep 2, 2010
    Posts: 456


    other than Dura Glass or All Metal, I don't think there is a waterproof poly filler....
  3. RDR
    Joined: May 30, 2009
    Posts: 1,497


    best to solid weld behind filler....why not?
  4. d.reese
    Joined: Feb 28, 2010
    Posts: 228


    Apply a sealer over the filler.
  5. davis574ord
    Joined: May 21, 2009
    Posts: 785


  6. The Shocker
    Joined: Dec 30, 2004
    Posts: 3,538

    The Shocker

    All Metal is best IMO ...
  7. Filler is not going to be your problem or the answer to your problem! WELD your patch solid with no imperfections! Even small pinholes will allow moister in behind your filler allowing your metal to rust, then your filler will loose adhesion from your metal and wa la, your filler pops off and everyone blaims the filler when actually it all began with your patch welding.

  8. rosco gordy
    Joined: Jun 8, 2010
    Posts: 648

    rosco gordy

    They do not make a water proof filler it will sock water in just fiberglas will without jel coat it needs a bareier coat to seal it!!!
  9. CharlieLed
    Joined: Feb 21, 2003
    Posts: 2,463


    Since plastic filler is just polyester resin and talc I find it hard to believe that it is possible for any of it to "wick moisture".
  10. The Shocker
    Joined: Dec 30, 2004
    Posts: 3,538

    The Shocker

    It will let water pass through it .I learned that the hard way as a teenager on a weld seam ...
  11. i never understood the waterproof filler thing. isn't the paint going to provide the protection from water, just like it protects the perfect metal body panels or are we talking submarines?
  12. Francisco Plumbero
    Joined: May 6, 2010
    Posts: 2,533

    Francisco Plumbero
    from il.

    If you don't weld it up as they say it will just bleed through anyways. You'll just be sick over it in 3 years instead of 2 by going this water proof ish route. The hole will rust and expand the filler.
    Yeah, I did this a few times myself. I'm a shamed. But these boys showed me the way and now I metal finish it.
  13. The Shocker
    Joined: Dec 30, 2004
    Posts: 3,538

    The Shocker

    If there is a pinhole or a few like say in the bottom of a door skin that you just smear polyster filler over the bare metal and it sees lots off water on the back side.It will eventually cause the paint to bubble on the outside as the water gets absorbed through the filler and rusts undernieth ...
  14. hotdamn
    Joined: Aug 25, 2006
    Posts: 2,414


    sounds like the guy is asking because he is afraid of the metal condensating from the backside and that condensation being absorbed and held in the bondo eventually causing the body work to fail and ruining a paint job.

    jeeze, will you guys tone it done a sec and just chill out with all the testosterone:)
  15. hows the water getting through the paint? or are you not painting both sides? leaving bare metal on the back is going to rust out. here in the northeast it's got to be covered.
  16. Mr48chev
    Joined: Dec 28, 2007
    Posts: 34,257


    I guess the first thing we should have asked is why you need a "waterproof" body filler.

    As the guys said the best thing is to weld the holes up so that there is no chance of having water get in from the back though a hole. And don't get worried if you don't have the supreme metalworking skills that the guys who answered above seem to think they have as I know damned well that I don't have that amount of skill or patience and never will and have to finish off the imperfections with a bit of mud.
  17. Exactly.

    I sectioned some new rocker panel pieces in, and there is no way to get to the backside to seal the seam due to being sub-floor boxes. I used weld-through primer...

    I don't want to use filler that will wick moisture if theres some pores in my weld. I just would like to use a waterproof filler first, then glaze over it with the regular stuff like rage gold.
  18. The Shocker
    Joined: Dec 30, 2004
    Posts: 3,538

    The Shocker

    Kinda tuff to paint inside pinch welds ,driprails ,etc.Im no master metal finisher, spend 3 or 4 years on a door kinda guy either.What i do is this :weld the seam or pinhole as best as i can possibly do then clean the bare metal with a wire brush as best i can.After that i ruff the metal up and apply a thin layer of "All Metal" aluminum epoxy (which is designed specifically for this kind of work) .Let it kick than flap wheel it flat to the surface.Apply regular plastic filler as needed on top of that to get the finish nice.Then prime and paint.Yes ,i paint the back side of the panel when i can get to it to do so.The "All Metal" is kinda like insurance to seal it up ...
  19. I thought much like you do but learned different. 25 years ago I chopped the top on my F-100. I pretty much metal finished it but not like I do things today. It was all bare metal and toothed up a little with a 36 grit disc and then a light coat of filler just to block out to final shape. Then a few coats of Lacquer primer. Life took a major change about then and the truck went into storage. It's been inside and dry for ever and just last year I finally got back to that project. When giving it it's first bath in 25 years the top looked like the Salt Flats, all curled and cracked and blistering up. None of this had ever been wet and the thickest the filler was was about 1/16" and I pretty much took all of it off with a putty knife. Just the moisture in the air had gotten through and rusted till the filler let go. Talk about weird, I should have put some kind of top coat on the primer. Would have saved the whole thing.
    No filler is water tight.
    The Wizzard
  20. 57tony31
    Joined: Jul 20, 2008
    Posts: 632

    from Woods

  21. Rogue63
    Joined: Nov 19, 2010
    Posts: 228

    from New York

    I am near the water and moisture causes havoc,I use undercoating behind the weld after and haven,t had any problems,I also use epoxy sealer for the primer.
    Joined: Dec 27, 2009
    Posts: 1,291


    Moisture / Water problems come from the backside. You have to do whatever you can to completely seal the backside. Some areas are nearly impossible to get to. Even so,
    I've "poured" POR-15 into seams to seal them. U-Pol makes Fibreall. This stuff is definately waterproof. If you can spread a coat of this stuff on the inside of a repair,
    it will also seal/waterproof the backside of any repair, seam, etc... Also, Epoxy Primer that is reduced by 5%-10% and then sprayed onto the backside of a repair will also work very well. You may have to utilize a "wand" attachment to get the stuff where it is needed. I have actually used a Undercoating Gun with a wand to spray Epoxy Primer and
    POR-15 in Rockers, etc... Make sure you put a couple of layers of Masking Paper -or- Plastic under the Rocker Panel, Wheelopening, etc.. to catch the run off of Epoxy Primer, or POR15.

  23. POR-15 in Rockers, etc... Make sure you put a couple of layers of Masking Paper -or- Plastic under the Rocker Panel, Wheelopening, etc.. to catch the run off of Epoxy Primer, or POR15.


    Just wondering, ever have the POR-15 plug up factory drain holes when doing this? I know that sh!t can build up pretty thick....
  24. CharlieLed
    Joined: Feb 21, 2003
    Posts: 2,463


    I believe that the problems that people have had with fillers is not because the filler is wicking moisture but because the metal behind the filler is corroding. This corrosion could either come from behind the filler, as stated through an open space in a weld, or from the edges of the filled area where the rust slowly crept under the filler until it undermined the bond of the filler to the metal. Lacquer primers were notorious for holding moisture, the very nature of these primers made them like a sponge to liquid. It's no wonder that any panel left in primer ultimately rusted if left unpainted.
    On pinch welds or other seams where I can't get to the back of the panel, I use either 3M 8115 panel adhesive or 3M 8306 heavy bodied seam sealer. These products provide a waterproof bond to the metal and strengthen the seam.
    VR&C gives good advice for the prep and treatment of the backsides of panels. I too run POR-15 or other similar products down into door seams to seal them up. After the paint has set I will run a popsicle stick through the drain holes to ensure that they did not clog up.
  25. overspray
    Joined: Jan 14, 2003
    Posts: 1,417


    or this from the Evercoat Marine line:

    A lot of primers, especially lacquer primers, contain talc to make them sand easier. (sp chk)

    There are some heavy duty industrial coatings that will perform better than the automotive repair materials that are available to the average Joe, but they are hard to purchase in small usable quantities for do it yourself. Coatings for the inside of storage tanks for oil and other products have much better properties to seal against moisture and chemicals.
    Last edited: May 9, 2011
  26. chaos10meter
    Joined: Feb 21, 2007
    Posts: 2,191

    from PA.

    A lot of primers, especially lacquer primers, contain talk to make them sand easier.

    Very true and at night when the shop is really , really quite , if you put your ear real close, you can hear them.

    I do anyway, I know they ain't real but sometimes they have really good ideas.

  27. Thats what happens with too much beer and smelling too much lacquer thinner. :eek:
  28. RDR
    Joined: May 30, 2009
    Posts: 1,497


    now that's funny;I don't care who you are....I'm going out in the shop and open a can of lacquer primer and have a conversation with it..:p
  29. Evercoats Fibre Tech (part number 100633) is a good product to use over welded areas. It has some flexibility to it so it won't crack but contains no talc so it doesn't absorb water.
  30. paintslinger1939
    Joined: Oct 1, 2007
    Posts: 49

    from Concord CA

    just spray undercoating on the inside. or epoxy prime the bare metal then undercoat it. both give corrosion protection.

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