Calling all metallurgy experts…

[Sarge23060]

I put magnetic QR codes on my CT to advertise my business. They were on the bare stainless for less than a week and when I took them off to wrap it, it looks like this underneath. Any clue as to why/if the magnet would do/did this? Haven’t tried cleaning with Citrisurf or Barkeeper’s yet, but SprayAway did nothing on it.

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[YukonJack]

Looks like water accumulated behind your sign where the magnets touched. As the water dried mineral deposits formed and layed on after multiple wet/dry cycles. Try Barkeepers - but do the whole panel so it doesn't show a shinny spot.

 

[RickJ19Zeta8]

Looks like the start of galvanic corrosion, which is caused by dissimilar metals. Use citrisurf 77+ and it should remove the deposited iron layer (yellow).

Barkeepers friend shouldn’t be used on stainless steel. While yes, it cleans the surface using oxalic acid, it doesn’t passivate the metal as it removes both the free iron AND chromium from the surface layer. It can also leave iron oxalates behind, which are really hard to remove and leave that brown look behind. It will also etch the stainless because it is so aggressive.

Citric acid is one of the acids called out in the ASTM spec for passivating stainless. You want to remove the free iron and leave a concentrated chromium layer on the surface. As that oxidizes, it will turn that nice very light bluish silver vs the crappy looking yellowish brown.

 

[Sarge23060]

Thank you both for your replies! I’ve been using CitriSurf 77 with great results prior to this, and it’s great to know it’ll probably work again.

 

[YukonJack]

For reference here is a thread that discusses all the opinions on this and the link to the "Out of Spec Detail".

https://www.cybertruckownersclub.co...avy-stain-removal-from-stainless-steel.17314/

The "Out of Spec Detail" video talks about the official tesla cleaning kit about 2:28.

The thread talks about CitriSurf 77 on post #38.

Lots of opions so you will need to decide which direction to go...

 

[Willinak]

I would not use BKF. Likely it’s just mineral deposits, and I would try something mild like white vinegar.

 

[HaulingAss]

Looks like the start of galvanic corrosion, which is caused by dissimilar metals. Use citrisurf 77+ and it should remove the deposited iron layer (yellow).

It's not galvanic corrosion and the stainless steel isn't rusting.

It's common rust created when the magnets attract iron brake dust from busy roads. Then the iron brake particles get wet and rust. That will stain painted body panels too. And it will be more problematic to clean up because you have limited paint thickness to work with.

Barkeepers friend shouldn’t be used on stainless steel. While yes, it cleans the surface using oxalic acid, it doesn’t passivate the metal as it removes both the free iron AND chromium from the surface layer. It can also leave iron oxalates behind, which are really hard to remove and leave that brown look behind. It will also etch the stainless because it is so aggressive.

The purpose of Barkeepers Friend is to clean below the passivation layer of the stainless steel. There is no way to do that without removing the passivation layer. After using BKF, I recommend washing with soapy water and rinsing well. This leaves the panels in an ideal state to self-passivate. The panels will self-passivate over a 48-hour period after using Barkeepers Friend to remove iron stains.

People are making this harder than it has any right to be. The stainless steel needs very little actual care and will clean up beautifully, even if you abuse it for years. I would avoid magnets on any car, especially on painted cars, and for the same reason, because it attracts iron brake dust and iron brake dust rusts. If you are going to use a magnetic sign, don't use one with individual magnets, use the flexible vinyl magnetic sheets.

 

[Seribus]

It's not galvanic corrosion and the stainless steel isn't rusting.

It's common rust created when the magnets attract iron brake dust from busy roads. Then the iron brake particles get wet and rust. That will stain painted body panels too. And it will be more problematic to clean up because you have limited paint thickness to work with.



The purpose of Barkeepers Friend is to clean below the passivation layer of the stainless steel. There is no way to do that without removing the passivation layer. After using BKF, I recommend washing with soapy water and rinsing well. This leaves the panels in an ideal state to self-passivate. The panels will self-passivate over a 48-hour period after using Barkeepers Friend to remove iron stains.

People are making this harder than it has any right to be. The stainless steel needs very little actual care and will clean up beautifully, even if you abuse it for years. I would avoid magnets on any car, especially on painted cars, and for the same reason, because it attracts iron brake dust and iron brake dust rusts. If you are going to use a magnetic sign, don't use one with individual magnets, use the flexible vinyl magnetic sheets.

I agree on making it harder than it needs to be. I did some overthinking when I first got mine. I didn't know what to expect. Saying that, what is your typical care routine? When removing iron?

 

[HaulingAss]

I agree on making it harder than it needs to be. I did some overthinking when I first got mine. I didn't know what to expect. Saying that, what is your typical care routine? When removing iron?

I can't say I've noticed any iron on mine. But I haven't inspected it with a magnifier because it wouldn't matter if there was some iron that I couldn't see.

My typical care is to wash the truck every two to three weeks with a long-handled truck washing brush and a bucket of soapy water (been using Maguires Crystal Wash lately, but whatever you have will work). I'm sure when winter sets in I'll wash a lot less often. If I feel especially industrious, I'll dry it post wash with a single microfiber rag, wrung out every minute or so.

My truck lives outside under the sun, rain, trees (needles, leaves and occasional spot of sap) pollen, oil refinery ash and birds. My primary parking spot is under the overhead electrical line to my house. Birds poop on it daily sometimes but it might go 4 or 5 days without too. I might spray the bird poop off with the hose sprayer if I see it in time.

Sometimes I spot clean with Sprayway Glass Cleaner which is great for fast and easy touchups of dust, fingerprints, fresh bugs, water spots, etc.

I have some non-abrasive Barkeepers Friend in a pump spray bottle that I use to remove spots that won't come off with the glass cleaner. I've found I can easily get rid of most stains without doing the entire body plane, just by doing it quickly, and feathering the cleaning action to the immediately surrounding area. Easy-peasy.

The great thing is it's just bare metal, no wax, no coatings, no fragile plastic wrap, just hard frickin' steel.

For about the same amount of effort that it takes to wash and wax a painted car, I can polish the entire Cybertruck from end to end, but that hasn't been necessary in the first half-year of ownership even though I've been beating it up off road in the mud and brush for the last six months. With painted cars I wax them several times per year. I'm saving a lot of time not waxing now. I did polish one side of the truck so I would know how involved it was, and how it would look. The stainless steel looks better than new, more uniform with a slightly finer satin surface texture that seems a bit more imperious to things since it's polished a bit finer. I can't see the 5mm orbital scratches the truck came with on the side I've polished (even though I used a sander with a 5mm orbit). Probably because I went with a 1000 grit polishing pad for the final passes.

If I had rust stains, I would use BKF, or the citrus-based product Tesla recommends, followed by a soapy water wash and rinse. I doubt it would even be necessary to polish the panels, just for rust stains. But you certainly could, if the quick fix method didn't work. Rust on a painted car is more problematic because the clearcoat/paint is fragile.

I love the toughness, easy care and high-tech appearance of the HFS. Especially the way it reflects the colors around it. Like this photo I took off-roading last week:

It's a game-changer to not have to worry about your fragile paint/clearcoat/PPF when off-roading. And the wedge shape of the Cybertruck parts shrubs, branches and small trees better than anything I've ever owned. All without any lasting damage.

 

[OldDirtyRobot]

Looks like the start of galvanic corrosion, which is caused by dissimilar metals. Use citrisurf 77+ and it should remove the deposited iron layer (yellow).

Barkeepers friend shouldn’t be used on stainless steel. While yes, it cleans the surface using oxalic acid, it doesn’t passivate the metal as it removes both the free iron AND chromium from the surface layer. It can also leave iron oxalates behind, which are really hard to remove and leave that brown look behind. It will also etch the stainless because it is so aggressive.

Citric acid is one of the acids called out in the ASTM spec for passivating stainless. You want to remove the free iron and leave a concentrated chromium layer on the surface. As that oxidizes, it will turn that nice very light bluish silver vs the crappy looking yellowish brown.

100% this. I'm not sure who started this Barkeepers Friend and Windex method, but you've done CT owners a great disservice.

 

[HaulingAss]

100% this. I'm not sure who started this Barkeepers Friend and Windex method, but you've done CT owners a great disservice.

Windex with ammonia is bad. I think that method was popularized by that Out-of-Spec Detailing YouTube channel. I'm not sure who started the rumor that Barkeepers Friend is bad. Sometimes you have to clean or polish below the passivation layer.

No worries, it will self-passivate again, that's what makes stainless steel such an amazing metal.

I would recommend avoiding the kind of BKF with abrasives. That will eventually polish the metal too smooth in the areas where you use it the most. Then you would have to repolish the entire face to make the surface uniform again.

 

[Seribus]

I can't say I've noticed any iron on mine. But I haven't inspected it with a magnifier because it wouldn't matter if there was some iron that I couldn't see.

My typical care is to wash the truck every two to three weeks with a long-handled truck washing brush and a bucket of soapy water (been using Maguires Crystal Wash lately, but whatever you have will work). I'm sure when winter sets in I'll wash a lot less often. If I feel especially industrious, I'll dry it post wash with a single microfiber rag, wrung out every minute or so.

My truck lives outside under the sun, rain, trees (needles, leaves and occasional spot of sap) pollen, oil refinery ash and birds. My primary parking spot is under the overhead electrical line to my house. Birds poop on it daily sometimes but it might go 4 or 5 days without too. I might spray the bird poop off with the hose sprayer if I see it in time.

Sometimes I spot clean with Sprayway Glass Cleaner which is great for fast and easy touchups of dust, fingerprints, fresh bugs, water spots, etc.

I have some non-abrasive Barkeepers Friend in a pump spray bottle that I use to remove spots that won't come off with the glass cleaner. I've found I can easily get rid of most stains without doing the entire body plane, just by doing it quickly, and feathering the cleaning action to the immediately surrounding area. Easy-peasy.

The great thing is it's just bare metal, no wax, no coatings, no fragile plastic wrap, just hard frickin' steel.

For about the same amount of effort that it takes to wash and wax a painted car, I can polish the entire Cybertruck from end to end, but that hasn't been necessary in the first half-year of ownership even though I've been beating it up off road in the mud and brush for the last six months. With painted cars I wax them several times per year. I'm saving a lot of time not waxing now. I did polish one side of the truck so I would know how involved it was, and how it would look. The stainless steel looks better than new, more uniform with a slightly finer satin surface texture that seems a bit more imperious to things since it's polished a bit finer. I can't see the 5mm orbital scratches the truck came with on the side I've polished (even though I used a sander with a 5mm orbit). Probably because I went with a 1000 grit polishing pad for the final passes.

If I had rust stains, I would use BKF, or the citrus-based product Tesla recommends, followed by a soapy water wash and rinse. I doubt it would even be necessary to polish the panels, just for rust stains. But you certainly could, if the quick fix method didn't work. Rust on a painted car is more problematic because the clearcoat/paint is fragile.

I love the toughness, easy care and high-tech appearance of the HFS. Especially the way it reflects the colors around it. Like this photo I took off-roading last week:

It's a game-changer to not have to worry about your fragile paint/clearcoat/PPF when off-roading. And the wedge shape of the Cybertruck parts shrubs, branches and small trees better than anything I've ever owned. All without any lasting damage.

Thanks for the detailed post. No fuss, no muss!

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