weld thru primer problem

[kancox]

I'm doing a double layer new metal patch,fender apron to kick panel,and am unable to plug weld. One layer solid the other 1/4" holes. Lay a nice looking plug in first layer but primer acts like a insulator and I get no penetration to second layer. I tried scratching primer off thru the hole, doesn't help. I've tried 3m weld thru II which is zinc base and SEM copperweld which is copper zinc inriched. Both aerosol cans.I'm using a millermatic 211 with .023 solid with argon voltage a little above 4 and turned wire speed down under 40. Any thoughts? thanks

 

[bax]

I dont use weld thru primer for the reasons you are stating.

 

[kancox]

Ahh so its not just me,i'll just use this stuff instead of liquid tape

 

[Timmy390]

I've used it many times and never had any issues......

Put in both outer rockers using it. They're solid as a rock.

Using a flux core 110v welder.

Tim

 

[kancox]

What brand and source did you use tim?

 

[Timmy390]

I used the 3M brand zinc based as I recall. Got it at the local body and paint supply house. It's been a few years so maybe they've changed the formula and it's not as good now?

I know with a flux core welder they run a bit hotter than the argon shielded. I tend to run my wire feed a touch slower than the setting call for.

Tim

 

[AZ73]

Use is all the time. No issues. I hope you're wearing a respirator. Heating the zinc is poisonous. Don't breath it in.

 

[mavereq]

Turn your wire speed way down

 

[jmangi62]

I'm with bax, I never use it.

 

[Montoya]

Try attaching your welder ground to the primered panel. I had a similar issue with my project and it just wasn't getting a good enough ground to complete the circuit and get a good arc started.

 

[allenfahey]

You also don't need a lot of primer for it to be effective. The copper stuff is junk. We had a bodyman at work use it and he switched and haven't had any more problems.

 

[kip60]

I was using 3M Weld thru II for the front floor pans. Thought it would help keep things sealed up better. Don't have a lot of experience in welding. It reacted completely different than the bare steel I was practicing on. Had similar experience that you did. Didn't get real good penetration on floor support or the floor sides I was plug welding into. Turned wire speed down, heat up a bit. That seemed to work better. Using 75/25 CO/Argon. I don't think I'll use weld thru for the rest. I'll just try to paint and seal after welding the best I can.

 

[Quick & Dirty]

.I'm using a millermatic 211 with .023 solid with argon

Straight argon, or CO2/argon? Mig welding with straight argon takes a lot more heat than with CO2/Argon.

 

[deltabronco]

You can weld through Rustoleum cold galvanizing.

 

[Canuck]

I agree with Montoya. sounds like a grounding issue. Personally, being a welder for many years and now a welding inspector, I would never use the "weld Through" primers. ! as mentioned Zinc is bad for your health when you breath it in and welding through paint or primer adds impurities to your weld as well as may cause porosity. JMHO

 

[allenfahey]

In auto body our industry standard is ICAR and for proper corrosion protection you must use weld thru primer. You have to use the correct weld thru primer and use it correctly. You aren't going for coverage, don't apply heavy.