I was using citric acid and 24 volts DC to passivate and clean stainless welds 20 years ago. It is not a new process. I liked it because I had to do work in breweries and kitchens. Very safe and non-toxic.
The stuff I used is called Citrisurf, by Stellar Solutions.
Fast Acting, environmentally friendly solution that better protects workers
improves and makes the removal of chromium oxide and heat tint from stainless steel safer. The new, 3-in-1 exclusive formula contains no hydrofluoric acid. It is available in a paste which can be applied by brush or sprayed on and a gel for dipping complex fabrications without the need for extensive PPE or the risks of hydrofluoric acid burns. When ready, it can be water-rinsed or wiped off with a damp cloth.
ProStar Stainless Steel Heat Tint Remover is water-soluble and employs "smart technology" that only attacks the oxides which cause the weld heat tint and reduction in corrosion resistance. And, when the oxides are gone, it turns off, protecting your fabrication - it can be left on indefinitely.
"The metal fabrication and welding industry has long-awaited this solution," said Chris Vihnanek, Director of Metfab Productivity at Praxair. "The ProStar line of worker- and environmentally- friendly products will save our customers a lot of time, allowing them to focus efforts on other ways to improve productivity and boost their bottom lines."
Praxair's ProStar line also features the De-RUST rust remover and DE-BOND paint and coating remover products which also employ "smart" technology which targets the problem areas, protecting the substrate.
Ok, I talked to our contact at Praxair, and this stuff is even better than they let on in the press release. It won't attack the stainless at all, only the various oxides, so the heavy-metal problem is vastly reduced. It's safe enough that you can brush it, spray it, or dip it (different versions of the material). If you rinse off hydrofluoric acid or the acid you're using with an electrolytic process, and let it settle in a tank, the draining frequency for hazmat purposes, by comparison, is only something like 1/4 as much.
I didn't talk to a guy who's involved in shipping, but they gave me a name and number for you to call. You want to talk to Mark Clemente at
1-262-938-6300. If calling is a problem for you from Australia, let me know.
Good luck with it, Jon. The guy I talked to is Larry Cherne, by the way.
It is available, Bill, and they have some big customers using it. I talked yesterday with one of the Praxair managers and he sounded annoyed that the website isn't up to speed with it.
You might have to call Praxair at 262-938-6300 and ask for Mark Clemente. If he's not available and you need to try for someone else, use the product name that's at the top of the press release I posted for Jon.
They'll catch up with their promotions. Praxair has a lot of products.
No, I didn't ask. I sent an email to them after talking to Larry Cherne, thinking I might write a short item about it, but I haven't heard back yet.
I think that most applications involve the three biggest TIG-welding stainless applications in industry: food-processing equipment (especially dairy); pharmaceutical processing; and industrial chemical processing. All three involve a lot of tanks and fittings. All three also are very specific about what methods are allowed. I don't know what fluxes are allowed.
It may just be a little bit too early. They've been selling it to some customers, but I was just going on a press release, except for what I got from Larry. They may not be actively marketing it yet.