Love it when someone else has done the hard yards and i just sit back and benefit without straining grey matter.I learned something today. Thanks Mate.

The only guy putting in the work to help everyone out! Keep up the great work

Perfect timing for me watching your video! I just came in from the shop after spraying UPOL Copper on my firewall weld surfaces! My research tells me the same thing that you did such a great job in showing. As an electrical engineer whom studied electric arc flash energies and temperatures for the last 15 years of my career, electric arc temperatures can get as high as 35,000F. I believe GMAW welding temps run between 3000-10000F depending on arc gaps and settings. Using it surely can help, surely some of it turns to gas in the mid point of the arc but as the temps drop going away from the hot areas of the arc, there will be a sweet spot where it can help reduce corrosion(edge of the weld where moisture could attack). My two cents........

I'm in the process of ordering weld through primer and found out there are two different types. Wanted to know the difference and this really helped me. So thank you for giving a detailed explanation to why and not only saying but this. 😀

Wow! Roger, Thank you for doing this video. I just started the same type of project, and made sure i bought a can of weld through primer...when asked the question, zinc or copper, I replied well, i'm welding sheet metal so i guess i need zinc instead of copper, and i was told i was correct. i knew it was bad to breathe, but now i am going to switch before i get any further along. keep up the good work. i have learned so much following you. Thanks again.

Remember that the arc itself is between 6,000 and 9,000 F. It’s why, in TIG welding, the tungsten tip melts. Check the melting temp of tungsten. Weld through is mainly there to protect metal where you can’t paint. So we’re talking about in between panels in a door, as an example. These panels shouldn’t be exposed directly to water, normally. Even if the weld itself begins to rust a bit, the rest of the panel is protected. If you paint the surface of the panels after welding, then the weld is protected on the outside surfaces, and the weld through is giving protection around the weld, almost like a gasket. It’s not perfect, of course, but it give some protection where bare metal has none. As far as the sheet used in modern cars, it’s ultra high strength high alloy steels, not low carbon. Those days are pretty much over. These new steels are far stronger than anything used before. If you wonder why panels are thinner than they used to be, that’s why. Some are up to 800 mega pascals in strength. Compare that to the older steels at about 200 mega pascals. They are also ductile, and easy to form. Welding them properly requires newer alloys of welding material. I hope that helps somewhat. I applaud your efforts in this area. It isn’t easy, considering all of the bad, and misleading information out there

My man your the only one on KZfaq that goes threw great detail with theweld threw primer. Keep up all the great work. I love watching all your videoes👍.

Good to see someone out there striving to do the best job possible. Keep up the good work.

This video is excellent, you did a great job of breaking it down and using science to backup your findings. Will be using this to do my project. I used zinc years ago and yes it rusted so this really makes sense. thank you for this

Thumps up Roger im sold on the copper . I think you did a great job making this vid . There is a ton of great info in it

Brilliant video full of great content .I will be using the copper in future for sure .Thank you for spending your on this research im sure many more of us will be using copper weld through primer from now on

Thank you. Just what my brain needed to finally decide which to use. Keep smiling..

Another factor is the change in the metal itself from the heat and it losing carbon . when you melt steel structure of the atoms changes . run a bead of weld on a flat plate with no primer and set it outside, it will rust worse around the edge of the weld because the metal has changed in carbon content ever so slightly . That is the reason back in the 80's i learned to soak thinned primer in between panels after welding , learned that from an older gentleman that taught me to paint and he learned it from the oil and gas industry with offshore equipment .

Nicely done. The zinc may give you a short term block from flash rust but lapped joint corrosion resistance sounds like copper is a lot smarter.

Chemistry doesn't lye. Copper it is! I don't know what 3M uses but they want two coats, clean the plug weld, then mate the panels, weld and use cavity wax. They go as far as certification in the collision industry requires a life time warranty but also want before and after photos attached to the repair order using a bore scope. Now, that is starting to add up just to get you car fixed, yet peace of mind for a builder for myself. If I do the work, I don't need photos. I just know it's done right the first time. DK, ASE Master since 78, retired.

Great discussion Roger. Some very interesting findings.

Thanks for the tutorial. I would have never thought about the weld thru primer turning into a gas. I wish I could give this video 50k thumbs up. Very informative. Thanks again. Take care.

Спасибо за видео! Благодаря вам я определился какой грунт мне нужен для моего любимого авто. Сейчас делаю восстановление его и необходим грунт для сварки. Не мог определиться до вашего видео.

The manufacturer even says the zink coating should be removed from the surface that is being welded the only benefit using is if you are welding a pinch seam the zink won't burn always the surrounding areas of the weld leaving behind the zinc since you are unable to paint the metal after the pinch seam is welded. Eastman even has a video on KZfaq showing the proper way "weld through primer"

Living here in Michigan finding ways to stop ruction is very important to me.

it seems like a logical explanation

One another consideration is the grounded copper in a resin binder out of the spray can will not hold the same melting point as the actual copper metal. If it weren't for the binding properties the grounded copper are encapsulated in, there will be a violent reaction between the two dissimilar metals caused by electrolysis. The resin binders holding the grounded copper together will break down at a much lower temperature. Keep up the great job!

If you want to go the extra step and do a pull test on welds to see the strength difference it would be interesting data. Personally I would think a spot weld is actually stronger than a pinch weld. Not sure about that one either. Love the videos, very informative and entertaining.

Great vid and explanation. Really appreciate you taking the time to document and share.

You mentioned turning up the heat . I tried it with lack luster results on a project . I thought in retrospect that I was not hot enough. Willing to try it again, interested in fixing up an older car and would like to confidently use a copper product.

very interesting video !! I recently started restoring an old french car and was reading about weld primers etc.. and came to your youtube channel. I know in europe, the new cars, after being welded and assembled they go through a zinc-solution bath for corrosion protection. Why not a copper bath ? I don't know ? maybe copper is much too expensive ? But maybe (just guessing) it also has something to do with rust protection. Zinc corrodes easier as steel. So they take zinc because it will sacrifice itself to corrode before the steel does. Suppose we take copper iso zinc : the copper is more difficult to corrode as steel. So the copper will not sacrifice itself to rust, but the steel will rust iso the copper. Just guessing and thinking, maybe zinc is better .... Anyway, after the welding, blow some very liquid anti-rust protection into the hollow spaces that will penetrate through capilair effect into every little hole

I'm sold on copper... Great analysis, thanks

THANK YOU !! I WAS JUST FIXIN TO BUY SOME AND AFTER HOURS OF RESEARCH LAST NITE . YOU DID A BETTER JOB KEEP IT GOING 👌 PS VFD HERE

Great information! Keep up these type of video's. Its always good to involve your audience. Very interesting!

Interesting, I was wondering if you might make up a few test panels. I always assumed that the paint was obliterated at the weld point at or behind the weld, but unlike normal primer it wouldn’t interfere with the weld strength or adhesion. I also assumed it would give you maximum protection in the areas where it remains. I’m using it in the sills of my Landrover and pumping it with cavity spray after.

thx for sharing the research and the knowledge, I use the copper weld-thru to be compliant but it's a nuisance--just trusting the industry to know what's best. Like you say at the end, some care does need to be paid to applying it. It seems like I remember 2 medium coats/15 minutes in between (instead of just slathering it on right before welding).

Great answer ,thanks a million

I'm going to check out the copper.

I looked at what temp a spot weld is and it says 400 to 500 degrees F. That is why they use zinc when building a car. Your video makes sense for mig welding though.

Great Video! Great Research! The only question I have now is, "Will the copper weaken the strength of the weld, since it doesn't boil away?"

Thanks for the great information and detailed explanation!

congratulations you found the goldfish!! knew you would get there eventually still shoot inside everything with the 360 spray wand when you finished welding and before preping the shell, it makes a huge mess if you do it right :) now, have i mentioned the skunk and the one eyed parrot yet?............................

Barb Sedo, I have never seen a rusted penny but have seen them corroded(green crust) and have had ro replace many copper plumbing pipes that have corroded away due to moisture.

I'm glad I watched this.

If you think about it, there must be very little zinc or copper in these primers. There is no way you can mig weld to copper or zinc, at least not with regular wire. I’ve been welding 22 ga .030” galvanized sheet metal on a late model car body, and if you don’t get all the zinc sanded off, even a trace of remaining zinc will destroy the weld!

Awesome video . I like your logic

I am wondering what happens to the chemicals (primer) that are added to it to help prevent rusting. As I understand it the copper is just meant as a conduit for the electrical current and not as a rust inhibitor. I'm just thinking since I don't know.

Alot of well thought through logic, but I doubt that is weld through primer underneath an original sill, or rocker as you call them across the pond. Far more likely the car was assembled with galvanised panels. Whilst the copper is less likely to burn away during the welding, of equal importance is it's ability to protect steel from oxidisation. Zinc is proven in that respect, but copper so far as I'm aware is not. Many years ago I visited Ford's Dagenham plant in the UK, and all welding was with bare steel.

Good video and good work but there is a case you are making there which is not quite correct. Material does not instantly change states, the change of state of the zinc from a liquid to a gas is not instantaneous over a given volume. Think about a kettle boiling, you bring the water to 100 deg C and it starts to boil off and yes disappear as a gas, but it doesn't happen instantaneously, depending on the volume it will take time, it will happen quicker as you increase the heat over its boiling point but still time is a factor. So it will all disappear as a gas in time, zinc will be the same it will disappear as a gas over time, depending on how much volume of zinc there is. The relationship between the volume, time and heat is complex here so will it all(the full volume applied) disappear, who knows. So thats a flaw in your logic, you are using something as an absolute which is not. That all said, it certainly makes the use of zinc more complex and less sure, it could well be the case that for spot welding where the time the heat is applied is very very short there may not be enough time for the zinc to boil off. It could be effective in an automated environment with very short heat cycles. But its unlikely to be very effective in a manual process, certainly TIG or MIG in your own workshop it seems highly unlikely to be effective, the copper appears on the basis of your work to be much more likely to work in practice for manual low volume applications where the heat and time its applied will have large variances. Great work and very helpful thanks, the video worked for me, I'll pay the money and go with the copper on my restoration, it has a better chance of working. Thumbs up.

From a scientific standpoint, you shouldn't be welding through any of these. From my research, they should be applied to both surfaces where they are lapped, plug weld holes marked on the mating surface and then removed in just those spots. Then welding the plug on clean metal to clean metal, as any welding instructor will agree is the only way to ensure the cleanest weld without contamination. The term weld-thru is a misnomer if you are doing things for the strongest welds vs. just getting it done. Now, that said, if the welds hold and don't weaken the vehicles ability to perform both on the street and in a crash AS DESIGNED BY THE MANUFACTURER, I say more power to you.

Quoted this video in a KZfaq chat.....and came back to sub.... you have great content keep it up!

Makes sense to me... 👍👍

Great work I do minor bodywork on my 86 foxbody. Looking for an answer other than using Zinc. I wonder does the copper have any side effects to the body like zinc does? Copper I think is a better solution to the problem. Eastwood has internal frame coating paint applied by a thin sprayer wand. You may want to look at that as extra protection against rust. I have used it on rocker panels to prevent rust from starting. Again thanks for the info>

I wonder what the copper does to the metal ? does it weaken the weld as it doesn't boil away? I just wonder if that is why they used Zinc so it would boil away allowing the metal alloys to meld together without contamination. I think there are a lot of questions. Liked your video, makes you think ;)

very interesting video I'm glad you did it but next question is are both products 100% zinc or copper

You say you’ve used science but you’ve only used it concerning the welding process. If you look at the galvanic table you will see that copper primer should not be used on steel because it is a dissimilar metal and will actually cause steel to rust faster. So anywhere you have coated in copper primer will now be rusting. I have a Nissan in my shop right now that had replacement rockers fitted in 2020 and it hasn’t seen the road yet. I’ve just had to cut off the previous shops work because they used copper primer and it’s causing it all to rust.

thanks mate great help

Mr. Professor: what temperature does rubber melt? I'm ready to see some tire smoke!!

My only concern with copper would be the strength of the welds it is between. I mean, you use copper backing to fill holes when welding because it doesn’t “stick” to the steel. With copper weld thru, would it not put a layer of this “unsticky” material between the steel pieces? I’m likely going copper as well, but that has had me scratching my head.

i'ma gonna follow you over to copper.

Very nice video!,,, thank you very much

Brilliant!

Well i dont know about you but i have spot welders my big one is 4.7kva non portable but i was testing zinc i could not achieve a good spot weld through the zinc at all. your results may vary.

Good stuff, Thanks.

Why not just flood the inside with phosphoric acid afterwards? Then cosmoline?...

where did you get yours & how much. I did a quick check & it was very pricey

Sorry Dude, you fail logic class. "pinch welds" on factory galvanized metal from the 70s are not the same as mig spot weld through modern zinc coating whose matrix is deigned to contain the zinc gas within the weld. Dude you compared apples and oranges and they simply are not the same! A modern zinc coating does NOT "just go away" in the 2 sec burst of a mig plug shot: The weod through primer contains a matrix to hold the zinc as it heats. As zinc changes state it enters the molten plug to galvanize it: THAT is the point of the zinc coating. Stay in your lane, and chemistry and thermodyanmics are clearly not your lane.

Love your videos, you’re research is the best but I have a question. If the copper only melts when you weld it would it contaminate your weld?

Amazon has the Upol 0768 weld thru primer available. They are calling it zinc/copper. Solids suspended in a paint does not have the qualities equaling electroplating. I wonder if the amount of metal solids suspended in the paint actually lessen corrosion and if galvanic corrosion is worth considering? Here is a site with some information about which metals are most and least likely to corrode: inspectapedia.com/BestPractices/Galvanic_Scale_Corrosion.php At the bottom of the chart labeled Metallic Corrosion Scale Terms is this: Note: Metals that have relatively lower resistance to corrosion, when placed touching another metal with higher resistance to galvanic corrosion, will act as the anode and will suffer corrosion. Example: copper pipe joined directly to mild steel or cast iron pipe will produce corrosion appearing more noticeably on the mild steel or cast iron pipe. Is weld through primer just another snake oil?

here is a question, if you spray zinc primer on top of copper primer with they react or is it fine?

nothing is going to keep a plug/spot weld from rusting initially...so, remove as little paint/ecoat as ness(dime size or less) prepare beforehand with access holes made or whatever to coat backside, flow into seams...we have fiber optics and bore-scopes nowadays...weld must be coated with something after welding,period. Otherwise you get what is sold at Barret Jackson for $$$$$ that has haS NOTHING!

How does it work with TIG welding

My take away on this. Epoxy prime the whole panel front an back, where my plug welds will be I should clean to metal, spray copper weld through front and back. Plug weld. Come back with thinned epoxy primer into the seams and soak. Followup with seam sealer?

Update : This is from DEC 2019 (after your video was posted). Your video is from FEB 2019. There is newer sentence from 3M official about copper weld thru. - kzfaq.info/get/bejne/nNqeeJB2v67DlGQ.html

I’m sold.

Try Steel it!

2 minute video made into 16 minutes lol

can you make a video on using epoxy with a syringe