I dont know if its the same primer, but I weld c-purlin and square tubing that comes primed all the time. I use the basic .035 ER-70S6 wire and C25/Argon gas. I run it hot enough to burn the primer off ahead of the puddle. I know its not as good as bringing it down to bare metal, but for those small insignifigant jobs, it has always worked for me.

 

The weldable primer must not be put on too thick. You can run into problems especially when welding with MIG. With SMAW ( stick ) It burns through the primer with little difficulty.
I have worked on some large jobs were the plate was wheel abraded then primed with weldable. It is nice for layout and fitting but can be frustrating for welder if he hits a thick spot.

 

I used Radnor Cold Galvinizing Compound prod #64000130. I did put on 2 coats 1 coat looked kinda thin. It was also breezy and he only had .030 wire which he knew was to heavy but my son wanted it done, you know how that goes. Thanks for the info.

 

problems welding thru cold galvanizing spray



Geez! Where did you get the idea that this cold galvanizing spray is a weld thru primer?

Maybe the 'Expert' counterman at Airgas?

Normally, it's intended to apply AFTER WELDING.

Welding on zinc compounds, is one way to loose teeth, etc. Not good for your health, plus
all the welding problems that come along with welding on galvanized.

Tube steel stock can come from the mill with either redkote or kleenkote primer, which is 'weld-able', sorta-maybe,
I sand/grind the areas that are to be welded.

 

I had heard `that welding galvanized was bad but the can even says "MIL-P46105 weld thru primer". I'm new at this and was not really sure about it.. What is the brand I should be using?

 

Not to worry. Most of the commercial weldeable primers are not a metallic coloured. The ones I have used were primer red or sky blue. Your weld through primer is an ideal application where as you say the hidden area will not be accessible after welding. My guess is you picked up from an auto repair supply house???
It goes without saying to stay out of the weld plume. Zinc oxide will not kill you. There are worse things in paint residue.
Or if you really want to go old school you could use red lead painted on all inside surfaces. This was common on riveted structures long ago. Lead poisoning from paint products was not unheard of in those days.

 

3M makes a weld through primer. Called..... 'Weld Through Primer'.
It comes in an aerosol can or a can with a brush in the lid, and is dark gray in color. It is loaded with zinc of course. I have used it many times and it works perfectly. No problems with zinc fumes either, like you get welding on galv metal.

You can buy this at an automotive paint store.
I get mine at my PPG dealer. I have seen it at a Sherwin-Williams (auto paint, not house paint) supplier also...... pg

 

Thanks guys for the help and info I know I'll be on the right path.