I have seen several references in posts about a weld through primer. What exactly is it? Also, I was looking at some PPG self etching wash primer. Is a wash primer the same as etching primer? What PPG etch primer should I use?

As always, TIA

Kevin

I have some PPG etching primer it also say wash primer on the can. I guess it's the same thing.

OK but what is weld through primer?

I have been using Sherwin-Williams weld through primer for a couple of years. It is in a spray can and is designed to be applied to bare metal in areas that are to be welded together. FOr example where two panels overlap eachother. I use it anytime I remove the spot welds to seperate a panel. Once apart, I clean a spray the bottom panel lip with weld through primer, place the panel over the top, and start welding. Make sense? Be aware that the stuff I use contains zinc, and a respirator should be used when welding. On another note, to me, it is a PITA to weld through. It spits and spatters like you wouldn't beleive. I'm not so sure if I like it or not, it just catches fire while welding and seems to burn away anyway. Maybe it still leaves the zinc behind for protection....I don't know. I boaught it at my local body supply shop.

Try the 3M weld through primer, let it dry good before you weld-follow the instructions. This is the best weld through primer I have used. I did my own product testing on quite a few brands of this stuff and 3M was the best for weldability and burnback. My testing also included a 1 month submersion in saltwater. In my opinion--******Stay away from the SEM brushable weld through primer!*******-I don't know how SEM can sell this stuff, I'm sure it's responsible for some very poor welds on the road today.

Another vote for 3M Weld Thru primer. Weld through primer is a coating that allows you to do what the name implies, weld through it. Anytime you plan to weld two pieces together where the metal overlapps, or when welding parts to flat surfaces, you should coat both surfaces with weld through primer as opposed to assembling the parts bare.

7D, another vote for 3M or just about any other BUT Sherwin Williams!

I did a comparison test with about six different weld thrus. The S-W (which I was selling as a S-W rep) was JUNK compared to the others. "Autotech" was the best at about 16 dollars a can. SEM was also very good. The "old" 3M was the best, but it is no longer available.

Apply just a thin coat, and LET IT DRY well. The S-W was just toooooo heavy, man it is like undercoat for goodness sakes.

Anybody use Norton weld thru primer :confused: That's what the jobber said most shops around here use. However I bought the 3M on everyones recomendation here. The 3M was $17 for 1 rattle can graemlins/angry.gif It says to use 2 light coats and let it dry for at least 15 min. before mig welding so I will give it a hour and keep reading here until I can go weld ;)

Yup The 3M stuff seem to be the best,from what Ive used. All of the weld through primers are supposed to be a corrosion preventitive sealer foe welding not corrosion proof.Clean stuff is happy stuff. I hate rust!!!