Weld-through primer

[autronicDSM]

What's the deal with weld-through primer? Can someone enlighten me on its proper usage? I tried using it once with very bad results. Basically sprayed both part, let it dry and then tried welding it. I got a lot of splatter and seemed like I wasn't getting any penetration? I tried adjusting wire feed speed and power but it ended up burning through. Should I have to adjust any welder settings? I can weld clean 20ga sheet just fine, but once it's primed it's like I've never welded before

If I'm welding two overlapping panels, should I just apply primer to the piece on the bottom that I wouldn't have access to once welded and then use regular primer or (in my case) Rust Bullet to spray over top panel and weld?

 

[Justin_l_]

I have used it a couple times. Never had to adjust the welder for it, welded just like clean sheet metal. I was using some stuff from napa, but not a napa brand. Sprayed it on, let it dry and welded.

 

[dalesmitsu]

Sand-grind paint down to bare metal, then weld it should fine and hold.

 

[bastarddsm]

Yeah, it's got zinc in it so it usually welds like shit.

Your supposed to paint the pinch weld areas with it.

What I have been doing latley is painting the pinch weld surafaces with POR15, letting it tack up, then putting it together and welding. It seems to weld thru pretty good. I then try and slop a bunch on the top of the weld and let it seep into the pinch weld.

 

[NWHTanK]

You are probly putting it on to thick try a thinner coat.

 

[autronicDSM]

You are probably right, I sprayed two layers to make sure it's nicely coated since it's shock tower. I'm trying to make it as rust proof as I can so I don't have to repair these areas ever again.

 

[buhay6]

Sorry to bring up a dead thread but I just picked up a can of U-pol weld through primer (copper) and am wondering if anyone's used it before? I've read a lot of mixed reviews on weld through primer

Any more info on the POR-15 bastarddsm? I've thought about using POR-15 on the surfaces I'm not going to be welding because I don't know how conductive it is or if it'll take the heat or not. But if your saying it works well to weld through then I'll definitely give it a shot.

Little back ground info:
I'm welding beck in the rocker panels under the doors of a 1g talon, so once its welded up I wont have access to it anymore.
Welder:
Thermal arc fabricator 181i (mig: Gas 75% argon, 25% CO2)

Only want to do this once so Help and opinions would be very much so appreciated.

 

[Blurred Talon]

I used U-Pol weld through primer on my car when I did all the body work.
Had no issues with it.

 

[NWHTanK]

Well when it comes to the lower parts of a car. I glue the pinch weld area and weld a butt weld with a backer at the seams.