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Thread: filler over welds

  1. #1
    Join Date
    Nov 2005
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    Lynchburg, TN
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    17

    Default filler over welds

    If you were installing a new quarter and had a 1 foot weld section,what kind of filler would you use over the welded seam? I am welding it solid, grinding it down and wire brushing it. Sometimes after it gets done you see a line. I have seen this when you put it in the sun and it gets hot, after it cools down it goes away. What do ya'll think is causing this? Thanks

  2. #2
    Join Date
    Dec 2005
    Location
    Maryland
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    86

    Default

    if you weld it solid, you should see no line from the welding. I seal all mt welds. I use either epoxy primer or Master Series urethane to seal the welds; best if it can be done front and back. Then I use, most times, regular filler. I have used short strand fiberglass filler, just depends on the area, as my first coat. You want the filler to not have any chance of getting wet. The fiberglass filler does that. But also, sealingthe weld with the primer does the same thing.
    Pete's Ponies
    Mustang RUSToration & Performance

  3. #3
    Join Date
    Jan 2006
    Location
    MICHIGAN
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    29

    Default

    i myself would consider the fact there may be pin holes.thus leading into using a waterproof filler,like lets say your choice of glass or metal type fillers.i myself do not like to take chances.from your brief description of the line you are seeing leads me to ask questions,like could it be a shadow from the smoothed weld or maybe an optical illusion?can you feel this line with a fingernail or by a flat hand?sometimg else to consider is the perosity of the different metals you have just combined from the weld.hope i haven't gotten too analytical here.:eek:

  4. #4
    Join Date
    Nov 2005
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    28,170

    Default

    I usually brush some epoxy prime over the seam then cover it with a layer of Ultra Glass milled fiberglass paste, sand or grind it then apply regular polyester/bondo-type filler to level the surface.

  5. #5
    Join Date
    Dec 2005
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    5

    Default

    are you butt welding or lapping it? I've seen ghost lines like your talking about from lapping.They only show up when the panel gets in the sun.

  6. #6
    Join Date
    Nov 2005
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    28,170

    Default Backing Strip

    Quote Originally Posted by yeepman2
    are you butt welding or lapping it? I've seen ghost lines like your talking about from lapping.They only show up when the panel gets in the sun.
    I usually advocate using the backing strip method. In most cases lap welding is harder to hide and doesn't do as nice a job while butt welding can be tricky for the novice. The backing strip gives the result of butt welding with the ease of lap welding.


  7. #7
    Join Date
    Nov 2005
    Location
    Lynchburg, TN
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    17

    Default

    I think the times I have seen this happen it was butt welded. I have caulked and undercoated the backside and still seen this problem.

  8. #8
    Join Date
    Nov 2005
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    Default

    Quote Originally Posted by Mcgoo
    I think the times I have seen this happen it was butt welded. I have caulked and undercoated the backside and still seen this problem.
    With a good butt weld you shouldn't get a read through line unless the two metal parts are a different thickness. Then the expansion and contraction of the different two parts may be different enough to generate a noticable line.

  9. #9
    Join Date
    Dec 2005
    Posts
    5

    Default

    Len,

    Would this backing strip work for metal adhesives as well? The only time i've seen ghost lines was on an oldsmobile that i glued quarter panel pathches on with. other than the ghost lines i was very happy with the repair, but i cant have ghost lines

  10. #10
    Join Date
    Nov 2005
    Location
    WI
    Posts
    1

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    I'm not len...lol.. but I think using the backing strip method with bonding would show a line...
    with bonding they recommend a lap joint and grinding the patch or repair panel to a knife edge to prevent ghost lines.
    Rick
    FIRST post on the new board!!!
    Very nice len!

  11. #11

    Default

    im pretty new to welding and have noticed a "ghost line" around the patch that i but-welded in to shave the gas fill on my truck.. I went over it again a little hotter and it went away.. is it possible that the line is from not gettin enough penetration? and if it happens again would it be risky not to fix it??
    Last edited by bs35j; 01-24-2006 at 01:49 AM.

  12. #12

    Default

    I've seen ghost lines show on but welds where the weld was not ground flush but instead left high and buried in filler, remember the steel will expand when heated and the thicker the steel is the more expansion that will take place.

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