Tiny rust spots coming through annealed (stained) Stainless Steel?

[Kev Williams]

echo what Scott just said, I engrave a ton of stainless (went thru seven 500gm bottles of Cermark last year!) and the only rust issue I can remember was from sanding transfer as I noted above....the same sheet metal shop sanded some aluminum sheets that were black anodized, right after sanding a ton of stainless, lots of silver streaks and small embedded flecks of stainless all because of careless sanding...

I'm thinking it's just a fluke.

As for what may work as a quick fix- get some Naval Jelly (phosphoric acid) and some Magic Erasers. Both are safe to use on stainless, the NJ will take care of any rust, and the ME will help do it quickly! Wear gloves, rinse well and dry...

re: Magic Erasers- while these things will quickly scratch acrylic, and just breathing hard seems to scratch stainless, I use them even on mirror-polished stainless with no scratching or hazing at all. Very aggressive use might, but just basic wiping, wet or dry, they work great. And you CAN get a bit aggressive with brushed stainess, just go with the grain.

[Jacob John]

Interesting Kev and Scott. These are 3 different brands of SS that I stained. Full disclaimer, each was left in the dishwasher after being washed for about a day. They are all supposed to be high quality SS bought from a wholesale distributor, and one is a pretty high end piece that I engraved as a gift. I'm trying to lock down the common denominator but the only thing I can think of is I did use a magic eraser with some Zep to take off the reside left from the staining. Maybe it took off the protective oxide layer as well?

[Scott Shepherd]

All of the cups I have ever seen have a disclaimer on them that says not to put in the dishwasher. If they are the Yeti knockoffs and you are putting them in a dishwasher, then there's your issue. We drop a small piece of paper with "Care guides" on them in every cup we do and it says "hand washing only, do not put in dishwasher". Too much stuff happening in a dishwasher, with hot water. That could very easily cause the issues, in my opinion.

[Gary Hair]

All of the cups I have ever seen have a disclaimer on them that says not to put in the dishwasher. If they are the Yeti knockoffs and you are putting them in a dishwasher, then there's your issue. We drop a small piece of paper with "Care guides" on them in every cup we do and it says "hand washing only, do not put in dishwasher". Too much stuff happening in a dishwasher, with hot water. That could very easily cause the issues, in my opinion.

. From what I have been told, the issue with vacuum vessels, YETI, Rtic, etc., is that the heat can break the seal and lose vacuum, rendering the piece useless. If stainless steel was harmed in a dishwasher then virtually every set of silverware known to man would be a rusted mess - the vast majority of it is stainless. It could be the passivation methods, but considering that a huge percentage of silverware is made in China, I doubt it.

[Scott Shepherd]

. From what I have been told, the issue with vacuum vessels, YETI, Rtic, etc., is that the heat can break the seal and lose vacuum, rendering the piece useless. If stainless steel was harmed in a dishwasher then virtually every set of silverware known to man would be a rusted mess - the vast majority of it is stainless. It could be the passivation methods, but considering that a huge percentage of silverware is made in China, I doubt it.

Absolutely it can can break the seal, which is bad. I’m also positive that just washing stainless in a dishwasher doesn’t make them rust. However, when you combine all the elements in this case, I’d bet that the dishwasher helped accelerate this issue.

[Jacob John]

Absolutely it can can break the seal, which is bad. I’m also positive that just washing stainless in a dishwasher doesn’t make them rust. However, when you combine all the elements in this case, I’d bet that the dishwasher helped accelerate this issue.

And maybe that's it. I'm thoroughly confused. It was several different brands, two of which are at least labeled 300 series SS. It should have a high enough nickel content to not rust, so either these brands lied about the high nickel content (which I don't believe), the dishwasher accelerated the rust (which definitely is sound reasoning), or there's something common among them that happened to cause it.

As a test, I have two pieces that I've left in water for the last several days, and neither have started to rust. All I did for cleaning these was use blue Dawn and water, NO scrubbing from a magic eraser, and NO Zep. So far, no rust.

Oh and just for clarity, the rust is on the exact spots where the SS was stained. The rest of the rusted pieces are fine, and I'm sure in scrubbing them, those sections got both scrubbed and Zepped.

[Scott Shepherd]

It’s not hard to make stainless rust. In my machinist years, I’ve seen it many times. Want to see it rust? Sand a piece and set it on a piece of wet wood and leave it.

Having said that, I’ve never seen it in the engraving world on cups. Keep in mind, 18-8 is most likely 304.

[Matthew Herrera]

I’ve engraved quite a few stainless Hydroflask and never had a rust issue. I can’t tell you what grade stainless they were but never saw one spot of rust. I’m really thinking the dishwasher had a part in this. High temps, and PH can increase corrosion rates in stainless. But then again our “silver ware” should all be rusting too.... is it possible this is some kind of galvanic corrosion? Different alloys in an electrolyte will cause galvanic corrosion when one metal becomes an anode and the other a cathode.

[Kev Williams]

just curious, what brand of detergent you using in that dishwasher?

[Jacob John]

just curious, what brand of detergent you using in that dishwasher?

It's those Cascasde Platinum tablets.

[Scott Marquez]

I sell welding supplies at my day job and I sell a product called Bohler "Blue one" used to pasivate welds on Stainless steel, which is a pretty tame product, I also sell "Red one" which is much stronger.
Scott

[Jacob John]

Just an update to this thread, but I went crazy and frosted a bunch of my personal flatware (18/0, and some 18/8) and then stained (annealed) a few bread knives and other kitchen utensils. I ran them through several dishwasher loads and guess what? The flatware is not rusting, but the stained knives are rusting like crazy. Now, the pieces I've stained range from some high dollar, high quality SS knives (my wife isn't happy about this ) to some garbage you buy at the dollar store. Made no difference. Is it the detergent, heat etc? Could I convince a few of you to try the same thing and let me know what it does? I can't stand not knowing what's causing this!

Maybe it's the quality of Houston water? Haha

[Brian Lamb]

Stainless steel knives are most likely some form of heat treatable stainless, and it will all eventually rust. You can't hold an edge on rust proof stainless.

[Jacob John]

Stainless steel knives are most likely some form of heat treatable stainless, and it will all eventually rust. You can't hold an edge on rust proof stainless.

So maybe there's the answer. The flatware isn't rusting, but all the knives are rusting. So if that is the answer, beyond hand washing and immediately drying, is there any treatment that would slow or impede rust?

[Brian Lamb]

Hard to say not knowing the exact material, but I would suspect the passivation process would help remove any "rustable" material from the surface that might have been raised, disturbed or uncovered by the laser process. At this point, you are pretty much at a try and see type situation. Oh the joys of doing one-off work on unknown materials.... you never know what might happen.