TheSamba.com :: View topic

Tue Jul 26, 2022 6:31 am

Just wondering thoughts on using weld through primer, is it worth using? I have seen a lot of mixed, and contemplating which way to go with before I weld the other one on.

The person prior used it for the passenger side.

Tue Jul 26, 2022 6:42 am

I personally have always used it ...since I learned about it's availability. I know some say it burns away, but it was explained to me how the primer becomes part of the weld and the zinc ( I only use the zinc style) really does help prevent corrosion. Also helps protect the surrounding areas. I don't have any lab testing HaHa but I feel my projects have held up far better since I started using it.

Tue Jul 26, 2022 7:08 am

It does burn away. Using Zinc weld thru primer is adding the very same thing they suggest to remove from galvanized surfaces due to the hazardous gasses.

Tue Jul 26, 2022 8:24 am

That is a hot topic right now! To use or not to use weld through primer! Wish I had an answer for you. What I know is what I have learned. I use the weld through copper primer. I spray both parts. I now remove the paint from the areas I will weld. Immediately after the welding area has cooled down, I spray some vinegar into the weld area and into the seam. This keeps the rust away and kills any that may form. I am certain there is no research on my method, but I am aware of a video made by 3M on how to properly use their weld through product. It is on YouTube. My take away from the video, was what I do now.

The biggest issue with weld through primers is them contaminating the weld puddles. It has some serious issues. I had this event occur welding in some on my 54. It caused the center on the weld puddle to have pores in it. And during the welding, stalagmites started to form. Those reminded me of those 4th of July worms!

Good luck! Look up that video from 3M. It has a lot of info in it!

Tue Jul 26, 2022 12:03 pm

VW_Jimbo wrote: …I use the weld through copper primer….

Copper is used as a backer for butt welds because steel does not weld to copper, not a good thing to contaminate the surfaces to be welded with.

Tue Jul 26, 2022 3:50 pm

From memory I believe 3M actually advises that the primer needs to be removed at the weld point.

The melting and boiling point of zinc and copper is less than steel so you’d expect any coating to flash off during the weld process. So you probably won’t get any coverage at the HAZ but surrounding area will be protected.

Also with zinc you run the risk of inhaling zinc fumes. Read up about “zinc shakes”.

Regarding treating steel with an acid like vinegar be careful that whilst the acid will chemically convert the steel it means the steel is now unprotected and will flash rust quickly. You need to protect the cleaned steel with a protective paint layer.

Tue Jul 26, 2022 5:25 pm

I just welded in my pans without the weld through primer. Based on my research it’s a toss up!

Tue Jul 26, 2022 7:10 pm

TDCTDI wrote: VW_Jimbo wrote: …I use the weld through copper primer….

Copper is used as a backer for butt welds because steel does not weld to copper, not a good thing to contaminate the surfaces to be welded with.

Product is a great weld through primer. Upol #2 weld through. I believe it to be a mix of copper and Zinc. Straight Zinc scares me a little bit, so I shy away from the full strength stuff. My brain has been compromised enough, through the years. Do not need any other substances causing me any issues!

I use it sparingly and spray both parts. Then go back and remove the copper spray at the weld point. This regiment has been doing great with no I’ll effects.

Tue Jul 26, 2022 8:16 pm

Good for you asking questions before jumping in... a lot of videos and topics are full of guys who are too smart to need any research before chopping out and welding in a critical body structure panel. You don't want to just *hope* you did it right, especially if you have kids in the car with you.

Yes.. 3M has some EXCELLENT technician training material! I found the 3M tech material by accident as I was researching using their seam sealer and panel adhesives but I've soaked up as much as I can. Here are a few links I learned from

https://www.tomorrowstechnician.com/spot-welding-is-a-requirement/
https://multimedia.3m.com/mws/media/1455397O/3m-body-repair-solutions-guide-canada.pdf

Wed Jul 27, 2022 3:54 am

https://www.youtube.com/watch?v=y317f2KP-z4&t=545s

Is a pretty good video on how to use it correctly, thanks for all of the 3M references for videos