after a moths or so welds show signs of rust

[eduardo]

The weld joints show rust, it forms a blister and it bleeds through the applied finish flat black paint on wrought iron solid 5/8" stock material window grill. suggestions on how to prevent, minimize or altogether avoid this condition.
Any recommendation will be appreciated

 

[zardoz]

A weld will definately rust without prior treatment. There are a few methods, one which seems to be in vogue now is using a weld through type of etch weld spray on primer. An ordinary paint or spray onto a weld will always rust through.

Bilt Hamber, do a very good range of rust proofers, apparently (according to forum members). I do intend to try them myself very soon.

Remember you should always "cure" a weld before painting, or it will come through, even with primer. A rust stopper will turn rust from an active oxide into an inert oxide (or even a sulphide, if i remember rightly ?)

 

[fingers99]

What preparation did you do before painting? Any primer?

I'm assuming MIG with gas?

 

[drivewasher]

How do you cure a "weld" ?