Rust after weld

[Antonio Ferniza]

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!!

[Wheelchair]

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

Wheelchair

[TS-Off-Road]

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.

[phaxtris]

i agree, wrong paint/prep

[tommyj3]

Use a better grade of primer and color top coat.

[dabar39]

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

[JHCHOPPERS]

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....

[beamwalker]

i paint immediadly after welding for the baked on look

[Antonio Ferniza]

Thanks guys!!! That is what I wanted to hear.. ... I agree with the paint issue, this is a dry - oven paint process, and don´t 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!!!

[Antonio Ferniza]

That is what I wanted to hear.. ... I agree with the paint issue, this is a dry - oven paint process, and don´t 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!!!

[Bert]

JHCHOPPERS and everyone else! Thanks for all the info!
bert