what's causing RUST on my Stainless Steel?

Those bits of steel that have been heated past incandesence to the 'sparking' stage by the grinder have lost their non-corrodable properties. The bits are so hot when projected by the wheel that they weld to the surface around. Each bit then rusts, and deposits that rust on the surface around it.

LLoyd

reeeeally big vat of nitric acid should do the trick.......

don't try this at home kids, or at least let me watch

I have been doing a lot of welding and grinding of 316L lately. After 316 has been heated for any reason it needs to be passivated to remove the free iron. I give the parts a 10-20 minute dip in Citrisurf 2250 between the grinding and polishing stage.

Would this work for electropolishing?

Randy Replogle

Try a can of anti spatter spray (welding) - we used that in repairs of SS road tankers for year and it always worked.

Just one. Google the phrase "passivating stainless steel" This is well known and common.

Cheers Trevor Jones

An engineer that used to work at Pratt & Whitney told me they used Milk of Magnesia in order to protect metal from welding splatter. He said that they specifically had to use the Philips brand, if someone bought generic, the entire project would have to be scrapped and done over.

Sounds a bit messy to clean up, though.

But if you had a dose of Delhi belly after a nasty curry the night before, ther'd be no excuse for not turning up to work.

Thanks for all the responses everyone. Here's my problem... due to the construction technique I need to use, SOME parts of the sculpture are completely FINISHED before I can do final assembly.

That's because once assembed, it would be impossible to put my final grind treatment on many locations.

WHAT ABOUT THIS:

Is there any sort of oil or coating I can apply that will keep the grinding sparks from sticking and yet wash off or presure wash off? (or peel off)???

Thanks,

James

If it is grinding sparks, try some PAM or equivalent from your grocery store. Why bother to wash it off. It is clear and won't hurt the stainless.

Dan

Y'know... If the final finish were that important to me, and a little extra cost and time weren't critical issues, I think I'd slather on a nice thick coat of paint - even a tough enamel -, do the work, then use a chemical stripper to remove the protective coating.

LLoyd

How about an aqueous gel? In firefighting we've got a substance known as AFG (Aqueous Firefighting Gel...sometimes the names are so descriptive) that puts a coating of, well, goo, onto a surface. Sticks well, rinses off with water, and isn't prohibitively expensive.

Here's a link of something he could try for proably low cost:

No clue on the price and I've never dealt with those guys, but it'd be an interesting experiment and worth talking to the vendor.

Hope this helps? Dave Hinz

Just curious, but what do you use it for in firefighting? It seems like it would work to protect surfaces.

I wonder if you could adhere some plastic or paper film to the surface, like the stuff that comes on sheets of acrylic or polycarbonate plastic.

It's very much like using a foam; it provides a coating, an airtight film. The fact that it has so much water in it helps it to have more thermal mass than just foam bubbles, and the slime stays there longer than the foam which tends to burn off. On barn fires, for instance, you can slime a side and as long as you don't let it evaporate off, that exposure is protected. It's messy but effective, and a couple rains (or a hose) takes it off.

Well, the sparks are hot. Any plastic or fabric coating would either burn or melt, making the problem worse I would think. You want something that has protection and a way to cool the spark; I think the slime is worth investigating.

Same stuff is in absorbant disposable diapers, I think. This is just far more diluted.

Check with a supplier to commercial bodywork and automotive paint shops. There is a product that can be sprayed on the walls of spray booths to keep the paint overspray from building up. Liquid Mask IIRC. Water soluble, should come off with a soak with a garden hose. Dunno what a 5 gallon bucket is worth, but I have sprayed a bunch of it onto walls. Should work for something like this.

Cheers Trevor Jones

Mig welding spatter guard / rich detergent solution? or even wallpaper glue?