3M Weld thru primer

[kamaroman68]

Hey guys I have something related to this thread in the fabrication forum also but thought it may be better suited in this area. What is the purpose of 3M weld thru primer and how do you use it? I was under the impression that you spray it between panels and weld over the top of it for corrosion protection. I sent pictures of some welding that I did on my vehicle and everyone seems to believe there is a contamination issue. I believe them so am I using the weld thru primer wrong. Thanks Chris

[baz67]

After I have used 3M weld thru primer I would never use it again. It caused so many welding issue that I can not begin to explain. You are not using it wrong. It just sucks.

[hotrodgary]

After I have used 3M weld thru primer I would never use it again. It caused so many welding issue that I can not begin to explain. You are not using it wrong. It just sucks.

LOL, Totally agree!!!!!

The stuff welds like it galvanized steel...the primer actually has a galvanized type material in it or whatever I believe?

Later,
Gary

[BRIAN]

Not really sure what you guys are doing with it but it works very good as a rust prevention coating. What does suck is trying to get it out of the can as the nozzle always gets clogged. SEM sells a cheaper version.


It is meant to be used ONLY in between panels and not to run a bead on top of it. If you try that it is like welding through mud. If say you have 2 pieces of metal that are being joined like a roker panel and 1/4. You would drill your holes for your spot welds, then coat , then assemble, then spot or rosette weld the 2 pieces together. It acutally works great for resistance spot welding. You then have to remove all traces of it with a wire brush or 3m pattie.

[hotrodgary]

Thats what I did with it, only put it where my panels overlapped But when I came back to do the spot weld it was a pain. The stuff didnt "weld thru" very well at all?

Maybe I used it wrong...doubt it though?

[parsonsj]

I used 3M weld-through a lot, especially in places where I didn't have access after the panel was installed, like rear wheelhousings, rocker panels, trunk drops, and quarter panels. I bumped the heat up a number, and it worked great. I'll use it again.

jp

[mikey]

Try putting a thin coat on the back part only. I use it or norton, kent at least 3 days a week. Tust me it makes a difference in the long run I've had cars come back wrecked again 6 mos. later that were already rusty.Haven't seen that with weld thru primer. Also after you use it wait at least 30 min. before welding and turn the can upside down and spray it until it no longer sprays any material out. I have also fond that if you don't fully shake it up about 1/2 way through the can it's too thick to spray anymore. Hope this helps you out.

Mike