Weld through primer question

G

gsauto63

I'm going to be spot welding an outer panel to an inner one and was wondering about using weld through primer to help prevent corrosion.

Does weld through primer prevent corrosion between the panels. Should seam sealer be used also?
 
Opinions here on the board vary, but a leading authority on collision repair (I-CAR) recommends weld through primer be used in pinch welds where there is no factory zinc coating, or the factory zinc coating is damaged or removed.

Yes, seam sealer should be used also in most cases.
 
I f there is any way to saturate the joint with epoxy primer after welding it, that's the way I would go.
 
crashtech;14145 said:
Opinions here on the board vary, but a leading authority on collision repair (I-CAR) recommends weld through primer
Click to expand...
I'm always looking for reasons in the different opinions, so could it be that the recommendations from (I-CAR) are directed at professional body shops that don't have time to treat the welded seam the epoxy way? Same reason they use etch primer instead of epoxy? For the original poster here is a link to the discussion on treating the seam with epoxy.
http://www.spiuserforum.com/showthread.php?1081-Epoxy-and-plug-welds&highlight=epoxy+seam
 
Everyone is entitled to their opinion. My opinion is that attempting to saturate a seam with epoxy after the fact is a nice theory, but the gaping hole in the theory is that there is no way to check whether the operation was successful. Weld-through primer, when done properly, is a sure bet. Performing both procedures might be a decent plan.

I won't be leaving weld-through primer out of the process until another procedure has been proven to be effective.
 
Actually, Chrysler now recommends not using weld thru primer. I have been told that it has even been added to the I-car training what Chrysler says about it. Hereis a link to an article from Mopar Magazine on Chrysler recommended proceedures.

http://www.moparmagazine.com/2009/nov-dec/installing_mopar_sheet_metal_part_two.html

I am not really convinced that weld thru primer really works. It seems to contaminate the welds, and I am not convinced that it actually survives the temps of the welding. It has been well documented that the adhesion of weld thru primer is not good at all.

I have seen many previously repaired vehicles with corrosion problems in the welded areas. Some have appeared to have been treated with weld thru, but with the amount of corrosion I could not say for sure.

Aaron
 
The reason Chrysler can tell techs not to use weld-thru is because nowadays all their panels have some sort of galvanizing or galvannealing from the factory. I am very careful to exclude zinc coated panels from my weld through primer recommendations.

The problem with applying this advice to restoration work is that with very few exceptions, we we are dealing with steel that is not coated with zinc in any way.

So an article describing repair procedures on brand-new vehicles is not compelling proof that weld-thru is inappropriate for the kind of work most of us are doing.

I know that my position swims against forum orthodoxy, but I really don't care. Nobody has presented me with any findings that would contradict my training and my observations, which are that zinc primer does help to inhibit corrosion.
 
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