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Need some body work help

Discussion in 'The Hokey Ass Message Board' started by jtbloye, Oct 28, 2009.

  1. jtbloye
    Joined: Mar 4, 2009
    Posts: 30


    I have welded some panels on my truck and I would like to know if I should use fiberglass first then bodyfiller or can i just use bodyfiller and if i only use the body filler will it crack :confused:
  2. manyolcars
    Joined: Mar 30, 2001
    Posts: 8,433


    Its been my experience that fibreglas will NOT stick to metal very long
  3. SlowandLow63
    Joined: Sep 18, 2004
    Posts: 5,953

    from Central NJ

    Fiberglass is the wrong way. Make sure the panels are fully welded in and ground. That means no pinholes at all! Seal it from the backside and use some filler on the front to smooth out the joint. It won't crack for a long time as long as you use it properly.
  4. 440shawn
    Joined: Sep 25, 2009
    Posts: 1,716


    Hey Bro! Now remember this is just my opinion. I have worked with fiberglass and the application was on a fiberglass boats. I have always stayed with fiberglass to fiberglass. I have used bondo on metal with good success and it really has not cracked. Make sure to buy a good quality bondo not the k-mart stuff. although it will work in a pinch I don't want to offend anybody. Shawn

  5. inliner54
    Joined: Feb 9, 2007
    Posts: 405


    Filler on the metal is fine. no pinholes in your welds and get the metal as close as you can (hammer and dolly) dont put 1 inch of mud on it. the fiberglass stuff is the hillbilly way for fixing things that should have been replaced.
  6. HotRodBen1987
    Joined: Jul 29, 2009
    Posts: 691



    What he said
  7. gafridge
    Joined: Oct 23, 2007
    Posts: 162


    You should not need much filler if you hammer and dolly it and get it close before applying filler.You don't want the filler to be thick at all,the least amount possible.The thicker it is,the more apt it is to crack down the road.Make sure no pinholes in welds as noted above.You should not need any fiberglass at all.Good luck.
  8. rcnut223
    Joined: Oct 12, 2006
    Posts: 1,247

    from wisconsin

  9. flamedabone
    Joined: Aug 3, 2001
    Posts: 4,920


    I'm gonna go against the grain, but...I almost always use a fiberglass impregnated filler like Mar-Glass on welded panel seams. Why? It is water proof and will keep water out of your repair.

    When you weld a panel, you may THINK you have it full welded with no pinholes, but in reality, that's pretty hard to do. It is a good idea to lay a thin coat of Mar-Glass over the weld seams then grind it down to flush, just in case. That way, the only Mar-Glass left is a teeny-weenie amount in any pinholes you may have. The Mar-Glass will keep any water from getting in the back side of the repair and fucking up your Bondo, or paint.

    Then, skim coat as you would any thing else.

    Good luck, -Abone.
  10. MarkzRodz
    Joined: Sep 12, 2009
    Posts: 533


    I've worked a several Body Shops in my days.
    2 of them were even the BigRig Trucking firms. We were always busy building wrecks,etc. I was involved in an argument with an Old Timer there,,the argument was wether Bondo absorbs water or not.
    I believed back then that it didn't.
    I called the 1-800 number and dammit it does allow moisture to move through it even absorb it and cause rusting under it.
    What Flamedabone said is exactly what I've been doing for 30 years. I get the MarGlass ~ TigerHair or Fiberglass Impregnated filler even with the strands if I can't find the other. I'll work that shit in with my fingers to force the filler into any pinholes. Then smooth it gently down and let 'er harden. Then I use 36 grit DA slow and easy and level it to where it's minimal in thickness.Then I use a good grade regular body filler. Then 80 grit that.
    And like was said above absolutely seal the back forcing the sealer with a brush or even fingers w gloves,etc.
    Remember to let it all sit a while to lose it's solvents before you pile anything on it. Those repairs will last for decades.
    Last edited: Oct 30, 2009
  11. roddinron
    Joined: May 24, 2006
    Posts: 2,677


    This is exactly what I do, there's really no way of knowing if that weld is water tight, I use a thin skim coat of duraglass over it then sand it back before I apply putty. Cheap insurance.
    The car I'm building now had a LOT of putty on it because the last guy must not have owned a hammer and dolly, and under all that putty, the metal was beginning to rust, that won't happen with duraglass or something similar to seal it first.
  12. chopolds
    Joined: Oct 22, 2001
    Posts: 5,927

    from howell, nj
    1. Kustom Painters

    Hey, guys, I've been fighting this war for a long time now........I know you guys have heard that using a fiberglass type product will help keep rust out...but it doesn't.
    Think carefully about it...if there's a pinhole in your weld, water gets into the pinhole, even if the filler material is entirely waterproof....the METAL is still rusting. the filler doesn't keep it out, it either traps it it, if waterproof, or absorbs it, either way rust is starting.
    Better to take care with your welding, and seal up the bacsides of all welds (and bare metal) with a good sealer/rustproofer.
  13. uniquecoaches
    Joined: Oct 26, 2008
    Posts: 264


    Weld metal panels in where there is rust? Shoot, us hillbillies just use expanding foam. Yup, you just let it expand until its done and then take out your buck knife and shave it down and presto all it needs is a skim coat of bondo. I also find that duct tape and chicken wire works gooder also. Okay, I actually have to agree with chopolds on this one.
  14. MarkzRodz
    Joined: Sep 12, 2009
    Posts: 533


    Likes been said,,,if it's all done bone dry and then sealed on the back side moisture can't get in for a very long time. I've even put spot lights behind the work looking for those pesky dreaded pinholes. I can understand if you're lazy and trap moisture to begin with or go over old Bondini,,though.
  15. nutajunka
    Joined: Jan 24, 2007
    Posts: 1,466


    It's easy to find pin holes by holding a light to the panel and looking at the other side for any light showing. Weld up the pin holes and your good to go, plus seal the inside, because it will be bare from welding.
  16. fordcragar
    Joined: Dec 28, 2005
    Posts: 3,179

    from Yakima WA.

    This is exactly the way to do it.
  17. Pete1
    Joined: Aug 23, 2004
    Posts: 1,969

    from Wa.

    Anyone ever hear of hammerwelding??
    No pin holes. No fiberglass, no bondo, no lead. Only bare metal.
    Just like original.
  18. 29nash
    Joined: Nov 6, 2008
    Posts: 4,544

    from colorado

    'glas it or bondo it. Either works. Seal the backside with paint to keep moisture out.
  19. alchemy
    Joined: Sep 27, 2002
    Posts: 16,842


    All you "Bondo and no fiberglass" guys are cracking me up (pun intended).

    What do you think Bondo is made out of? Pixie dust and Superglue?

    Bondo is just fiberglass resins with a filler material (microbeads?!) in it. The only reason it is any more flexible than regular fiberglass is because there is no glass fibers holding it rigid. The gooey chemicals are the same. The adhesion is the same. And if Bondo will supposedly soak up moisture more than regular fiberglass, it is just the filler beads soaking, not the resins.

    Now, I was taught to apply just as Flamedabone and a few other guys above are saying. A thin coat of Mar-Glas, then Bondo on top for fine tuning. But, you gotta make sure to seal the backside with plenty of paint and/or undercoating.
  20. 49ratfink
    Joined: Feb 8, 2004
    Posts: 18,055

    from California

    I say rather than using fiberglass because you may have pinholes weld your patch up right. what are you guys doing wrong where any pinholes are not visible?

    there is absolutely no reason to use fiberglass in a metal repair. none. nada. zip.
  21. mlagusis
    Joined: Oct 11, 2009
    Posts: 1,042


    try running a bead of seam sealer on the back side, then apply your plastic filler. I use the "rage ever coat gold". it's a little more expensive, but is a good product. After your done you can paint over the seam sealer on the back side and you should not have any problems.
  22. fordcragar
    Joined: Dec 28, 2005
    Posts: 3,179

    from Yakima WA.

    Weld it, metal finish it, prime and paint; isn't that easy, no fillers to soak up any moisture.
  23. PegLegStrick
    Joined: Aug 8, 2007
    Posts: 1,883


    Never have seen fiberglass to metal that didnt crack. expands differently. Try sticking with metal and try not to put Filler too thick, It'll crack too if its too thick.
  24. jakesbackyard
    Joined: Feb 13, 2007
    Posts: 761

    from ND
    1. Upholstery

    That's the correct way. Duraglass, Everglass, Marglass, and Fibertech are all good for directly over the welded areas. They all use regular filler hardener so they are all polyester fillers with fiberglass strands of varying lengths as an ingredient. They make the initial coat waterproof - which is what you want.

    Don't confuse them with fiberglass resin and cloth. Not the same.

    Finish with a good grade of regular mud.
  25. SlowandLow63
    Joined: Sep 18, 2004
    Posts: 5,953

    from Central NJ

    And we'll continue to fight it........ :rolleyes:
  26. carcrazyjohn
    Joined: Apr 16, 2008
    Posts: 4,844

    from trevose pa

    I always skim coat with mud ,Bondo Then Tiger hair and then smooth out with more bondo Never had anything crack That is only for deep fills ,Bondo is fine up to 1/4 of an inch I prefer thinner .Anything you have to fill about an inch Should be fixed
  27. Stevie Nash
    Joined: Oct 24, 2007
    Posts: 2,999

    Stevie Nash

    So I am a novice MIG welder and I've got some pin holes on some patch panels on my firewall. All of the grinding of the hard welds is time tedious at best. Not trying to take the easy way out here, just trying to be more efficient. Wouldn't it be better to weld the pinholes from the backside (if you have access) so you will have less weld to grind from the front? Just a thought.... somebody shoot holes in my theory.
  28. Tinbasher
    Joined: Feb 13, 2007
    Posts: 274


    Well lets go one step further. Once your metal work is done and every thing is hammered and dollied out. Then you sandblast the repair and apply two good coats of epoxy primer. When this is dry, scuff it with 120 grit sandpaper and apply a fibreglass based filler to the weld area. Sand this off with 80 grit sandpaper and then apply your body filler over the repair area until you get it to shape. This repair will last 3 times longer than the one with no Epoxy. Why? because the epoxy primer adhere's to the metal, has zinc in it to fight corrosion and the oxygen created when the filler hardens can not attack the bare metal and form rust. Also the epoxy resin works hand in hand with the resin in the filler. Try it, you'll be surprised how well the filler sticks to the epoxy primer.

    Canada, Snow Cold Salt tough on Cars.

    "The Old Tinbasher
  29. roddinron
    Joined: May 24, 2006
    Posts: 2,677


    I should have mentioned, I always do this as well, but I stand by my choice of duraglass over the outside of the weld area.
  30. blt2go
    Joined: Oct 27, 2009
    Posts: 551


    grew up in a collision shop, dad specialized in vette's. dynaglass or marhyde was applied over clean, ground, dry welded areas before bondo if needed. now i do more resto and rod work i metal work all areas to within a frogs hair. then etching primer followed by high build. if my frog had unusually thick hair that day and imperfections aren't blocked out by that then a skim of rage bondo always does the job. i have found i'm better at patch panels since i bought a tig. (less grinding and no pinholes) the key is getting a good sealer coat on the back side. it's been mentioned you're not doing the outside any good if it just rusts out again from inside.

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