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Thread: Rust after weld

  1. #1

    Unhappy Rust after weld

    Hi Guys! I have a problem, I am MIG welding on carbon steel, after a while when the part is welded and then painted, it comes up some rust on the weld areas, do you know what may cause this defect, how can avoid this? Here is a picture of the defect.

    Thanks!!
    Attached Images Attached Images

  2. #2
    Join Date
    Nov 2006
    Location
    Hampton, Va.
    Posts
    386

    Cool

    Looks like you need to paint it with a good quality primer before applying your finish coat.

    Wheelchair

  3. #3
    Join Date
    Jan 2007
    Location
    Midland, Mi.
    Posts
    313

    Default

    Welds are fine, just poor paint prep. If possible I usually abrasive blast parts that need paint then wipe down with some naphtha or acetone. Epoxy prime, some urethane, and it's as good as it's gonna get.

  4. #4
    Join Date
    Mar 2007
    Posts
    356

    Default

    i agree, wrong paint/prep
    mm210
    maxstar 150

  5. #5
    Join Date
    Feb 2007
    Posts
    3

    Default

    Use a better grade of primer and color top coat.

  6. #6
    Join Date
    Mar 2007
    Location
    Vero Beach, fl.
    Posts
    761

    Default paint prep

    I would tend to agree with these other guys, clean it real good and use a primer and top coat. I have seen some guys use water based coatings and got the same results you got.
    Dave
    If necessity is the Mother of Invention, I must be the Father of Desperation!

    John Blewett III 10-22-73 to 8-16-07
    Another racing great gone but not to be forgotten.http://video.google.com/videoplay?do...modified&hl=en

  7. #7
    Join Date
    Sep 2006
    Location
    Maryville, IL
    Posts
    75

    Default

    Bare Metal needs to be Etched Primed before Primer is applied. Blow off all the loose dust, wipe it down with Final Klean, then Tack Cloth it off. Apply the Self-Etch Aerosol Primer to the bare metal, this will bite into the raw metal so the primer will stick.

    If you want to learn more about about painting, click the link:

    http://www.jhchoppers.com/projects/paint/paint.htm



    Hope this helps a little....

  8. #8
    Join Date
    Feb 2007
    Location
    asheville n.c.
    Posts
    618

    Default

    i paint immediadly after welding for the baked on look

  9. #9

    Talking

    Thanks guys!!! That is what I wanted to hear.. ... I agree with the paint issue, this is a dry - oven paint process, and donīt think that something may be wrong with the weld, CO2 could leave kind of a soot if it is used in excess, but I have 95/5 mix very well controlled, let me do some research on the paint process and see if something is wrong...

    I appreciate your help/opinions guys!!!

  10. #10

    Talking

    That is what I wanted to hear.. ... I agree with the paint issue, this is a dry - oven paint process, and donīt think that something may be wrong with the weld, CO2 could leave kind of a soot if it is used in excess, but I have 95/5 mix very well controlled, let me do some research on the paint process and see if something is wrong...

    I appreciate your help/opinions guys!!!

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