[GMP]

Hello, first post here. Learned a lot from Jody’s content. I’ve been learning Tig for six months now. Have a fair amount of stick experience in the past building 4x4 truck stuff and a trailer. So far built a custom stainless roof rack for my wife’s car using Tig. Also some aluminum repairs on dirt bike parts like skid plates, hubs, castings. Progressing reasonably well with the Primeweld 225. I have a basic question I have not seen asked. Of course I have dipped and stabbed tungsten with the filler like everyone else. Rather than cut a section off each time I have been tossing them in a container of Muriatic Acid (HCL) overnight, and then buffing off the oxide left with a scotch rite pad with the tungsten chucked in a drill. Once rid of aluminum I sharpen and blunt in a diamond wheel tungsten grinder. All seems fine doing this I just wondered what you think and why I have not seen this done before. BTW, my tungsten for SS are kept separate. Thanks !

[tweake]

i have not heard of that before, so i don't really know.
however i just regard tungsten as an expendable and just cut it off. i'm still on the same packet i got many years ago, so its not really an expense worth trying to save. cleaning with acid sounds like more work for minimal gain.

[Jack Ryan]

Aside from the cost (time), dipping will likely change the characteristics (doping) of the tungsten.

I have not tried but I expect that will change its work function and therefore arc starting and arc stability - including partial rectification.

I'd just cut it off or replace it.

Jack

[GMP]

Thanks for the replays. From a chemistry perspective, it seems fine as aluminum is highly reactive to HCL and tungsten non-reactive. Whether the doping (2% lanth) is affected is unknown (will look into that) but the surface finish of the clean area of the tungsten does not change. Also, at least at my level, I can tell no difference between using this method, new fresh tungsten, and cutting off the contaminated end. Its actually not that much work at all. Just wondered if there were any personal negative experiences. I work for a division of Linde and will run it past our material sciences guy.

[cj737]

I have 2 thoughts: first is, why immerse the tungsten in acid? A quick regrind and twist with a ScotchBrite pad turns tungstens back to a bright shiny level. Heck, I don’t even polish mine up 99% of the time. Second, I can’t imagine that introducing acid into a plasma arc has benefit, in fact, it may be creating some pretty toxic atmosphere.

You’re the first person I’ve ever heard of undertaking this approach in nearly 40 years of burning rod. That alone should be an indication of the merit of your practice.

[GMP]

I have 2 thoughts: first is, why immerse the tungsten in acid? A quick regrind and twist with a ScotchBrite pad turns tungstens back to a bright shiny level. Heck, I don’t even polish mine up 99% of the time. Second, I can’t imagine that introducing acid into a plasma arc has benefit, in fact, it may be creating some pretty toxic atmosphere.

You’re the first person I’ve ever heard of undertaking this approach in nearly 40 years of burning rod. That alone should be an indication of the merit of your practice.

That's the reason I asked, because I have not heard of it being done, but unless you have a negative personal experience, that does not mean its wrong. Arc is normal. I'm not a pro welder, I'm an engineer, so look at things from a different direction. I'm talking about cleaning a "QTip", a lot of aluminum from the tungsten. No acid remains, its rinsed off and the tungsten buffed and sharpened. So, no foreign material ever touches the diamond wheel. It simply saves a cut operation. I toss fouled electrodes in a jar and clean them up the next day, easy.

My material science buddy here says its no problem. While lanthanum alone is reactive in HCL, it is bonded very strong to the tungsten in the alloy, with no ill effect. He commented that in grad school experiments with a plasma arc furnace they would clean the tungsten electrodes the same way.

[Arno]

I suspect the risk is tiny to non-existent, but as it's known that a welding arc can create phosgene gas (COCl2) I'd keep any chlorine compounds away from either your workpiece or your tungsten. The carbon and oxygen in the formula is easy to get from normal contamintations and muriatic acid (HCl) residue can be a source of chlorine.

Again.. In all likelyhood still a non-issue, but at a 50 ppm lethality of phosgene it's not something you want to take risks with. Better safe than sorry I'd say.

Bye, Arno.

[GMP]

Concerns noted, but confident no chance of any acid residue left. There is probably a higher risk while working with a cast repair that had unknown exposure, and that's something that would be seen fairly often in a welding shop I would imagine.

[cj737]

Concerns noted, but confident no chance of any acid residue left. There is probably a higher risk while working with a cast repair that had unknown exposure, and that's something that would be seen fairly often in a welding shop I would imagine.

Competent and experienced shops have cleaning and preparation protocols to avoid contaminated materials prior to welding, cast metals included.