19 replies to this topic

[lctriples]

Thanks to forum members I have finally sorted mig welder out, but have another question related to welding. What is the advantages of using weld through primers? My car will only be on club reg and won't really be exposed to rain. I will seam seal all edges under car in factory locations so I really don't envisage any water getting into car. If I don't prime bare metal surfaces that get pressed together such as guards, sills or internals will humidity and condensation still create rust? I have tried two products wurth zinc based and body worx copper based, without a great deal of success. Most likely good products but I am obviously doing something wrong. Tried sanding back to bare metal on all surfaces before spraying but still didn't work. I have worked out not to spray top surface as welder wont arc, I'm talking about painted inside surfaces that press together only, then painting outside surfaces as per normal. Basically will I get into trouble down the track if I don't seal inside surfaces before welding . Once again any help/advice appreciated.

[lctriples]

Thanks for that bomber, don't reckon i'll be around then, leave it for the grandkids to worry about! cheers paul

[lctriples]

Thanks mark, what brand and where do you buy from, what would happen if you just used normal everyday primer, say from bunnings. thanks paul.

[grumpy xu1]

Roberlo make a good one, but upol is pretty cheap, buy it at a welding supply shop. just don't put it on thick, do your weld, grind smooth, 2 pack epoxy etch, then repair ect. Gary.

[Bigfella237]

Weld-through primer is designed more for spot welding then any kind of arc welding. But anything is better than nothing!

 

The factory use that mastic sealer stuff between bolt-up panels and that seems to protect bare metal just as well as paint does.

[grumpy xu1]

I thought he was talking about welding panel steel ? Using a mig ? Not what i would describe as arc welding & he's trying to prevent sweating & rust between the panels. So I'd use weld through primer myself but make sure the gap is tight. Gary.

[Bigfella237]

I was including MIG & TIG welding within the "arc welding" umbrella, not necessarily just traditional stick welding.

[tuxedoss]

The zinc based weld through primer like Wurths is great stuff and is far better than bare steel but I found the mig doesn't like it, heaps of splatter and basically crap to try and plug weld through. I then tried the Upol copper based stuff much less splatter and pretty easy to weld through but probably not as weather proof as the Wurth zinc stuff but still far better than nothing. Also found if plug welding was much better if you ground off a bit of a circle on the base panel where your plug welding, still gives you some protection either side of weld. But remember from the factory it was always bare steel between panels so if you can seam seal and keep moisture out its not a big deal and as bomber says your probably good for 40 years

[jaselx]

I use UPOL copper weld through primer with a MIG for "Spot Welding" panels together. Spray panels lightly both sides, clamp together and then clean the bottom of each hole in the top panel with a small end mill in a drill.

I have tried the zinc based primers before - UPOL & Terosen but they seem to react more with Mig Arc and spit & pop causing crappy welds.

[lctriples]

Thanks for feedback guys, as I mentioned car won't see a lot of rain but was worried about moisture getting trapped between panels. Don't think will be an issue as when I was unpicking a lot of spot welds, was mainly where water had come in contact/trapped in panels that rust was a problem. Internal joins were pretty good, regards paul

[grumpy xu1]

If you're really concerned after painting and if you have any acess just squirt some "new" oil in between anything you can't make water tight. Nothing rusts with oil coating really & its simple "don't" use old oil for obvious reasons though ! Gary.

[lctriples]

Good idea gary, I will also squirt with fish oil and cavity wax just to make sure!

[grumpy xu1]

Just use thin engine oil & atf & shell enzis fluid mixed together won't rust & doesn't stink. Don't be surprised if the steel is dry in a month because it soaks it in, just squirt again. You can use those spray bottles for like $2 @ woolies ect like your mrs would spray her hair with, the thin oil gets right into crevises & will walk around edges too. Gary.

[rodomo]

Great thread. I now know which direction I'll take with my build.

[IMORAL]

Great thread. I now know which direction I'll take with my build.

Which is?

[rodomo]

Get the welds right and spray some goop in after.