SS passivation a myth?

[Jako]

So I was working on deep cleaning all my stainless just now. And I started to look into this magical stainless steel passivation.

When I worked construction we never had wipe down any of it with acid so why our brewery gear?

Well after reading more on fourms on the process itself it sounds like stainless dosen't require passivation it dose so naturally. Probably why its stainless to being with right. Monkey see monkey do I guess.

I feel like this is a load of nonsense some big gear companies tell everyone to do once a year. Could it be the use of poor quality stainless? trying to have customers cover up impurities by using this step?I would imagine poor quality wouldn't be as stain resistant as a pure 304 would be.

I am thinking of skipping this step to save money and time. Also as gear gets bigger this becomes almost impossible. Stop me if I am wrong please.

Who else has never done this or has stopped. I would like to know why out of curiosity.

 

[day_trippr]

This could be entertaining, but it's too early to make popcorn here.

But, passivation comes in degrees and effectivity. I wouldn't be too quick to dismiss it as there are factories that seem to do it...

Cheers!

 

[Jako]

Definitely too early for popcorn. Unless someone can convince me otherwise I will skip it untill then.

I know some welders will do it but that makes sense to me.

 

[Bilsch]

First it’s good to understand the terms used in this process and why each is done. Generally speaking stainless is an alloy of iron, carbon, nickel and chromium with other elements based on the different types. But chromium is the most important element because it protects the alloy from rust by oxidizing in air and forming a surface layer of chromium oxide that is passive. But this layer is not perfect because there also is free iron at the surface. So we treat the metal to improve this passive layer by using certain acids to dissolve the iron from the surface and, to some small extent, the subsurface as well. This is the first step in the process and is known as enrichment, since as iron is removed the stainless surface, it is essentially enriched in the relative amount of Cr. The next step happens in the presence of air when the newly exposed chromium is oxidized, thus improving the passive layer. There are two acids used in the metal finishing industry for this, nitric and citric. HNO3 is an oxidizing acid so soaking in it not only removes Fe, it also oxidizes the Cr at the same time. Citric acid on the other hand only removes iron and the chromic oxide layer forms later. Citric is cheaper and safer to use, and according to NASA works better, so in the end you get a thicker passive layer. Therefore do it, or don’t do it depending if you want to improve the corrosion resistance of your gear.

 

[Bilsch]

Sorry guys, this really isn’t contentious so you probably won’t get a chance to enjoy your popcorn.

 

[RPh_Guy]

So do it, or don’t do it depending if you want to improve the corrosion resistance of your gear.

Just want to add a couple things:

Part of the reason for passivation is that the surface iron is chemically reactive. Iron accelerates staling reactions for example. Therefore removing it makes the surface more chemically passive, hence the term passivation.

Corrosion seems to be an uncommon issue, although YMMV.

 

[Bilsch]

Just want to add a couple things:
Part of the reason for passivation is that the surface iron is chemically reactive. Iron accelerates staling reactions for example. Therefore removing it makes the surface more chemically passive, hence the term passivation.
Corrosion seems to be an uncommon issue, although YMMV.

Heh.. I left that part out specifically in an attempt to make it a less contentious issue.

Time to break out the popcorn I guess.

 

[Franktalk]

The whole "popcorn" thing, for those who aren't HBT veterans is that passivation of stainless steel is a controversial topic or idea. But it doesn't have to be. It may be that the OP is innocent and uninformed and is therefore asking a sincere question. Let's proceed on that premise. Though, the usual know-it-alls may very well hijack the thread and proselytize their views to the uninitiated.

 

[Jako]

Sorry guys, this really isn’t contentious so you probably won’t get a chance to enjoy your popcorn.

You killed the buzz with lots of information and facts to back it up.

 

[Jako]

The whole "popcorn" thing, for those who aren't HBT veterans is that passivation of stainless steel is a controversial topic or idea. But it doesn't have to be. It may be that the OP is innocent and uninformed and is therefore asking a sincere question. Let's proceed on that premise. Though, the usual know-it-alls may very well hijack the thread and proselytize their views to the uninitiated.

It wouldn't say I'm I'm trying to be controversial. But the more I looked into it the more I noticed it's not white and black. As you can get away with not doing it. I never read a post of someone asking why a beer didn't last on the shelf for 5 months and it end up being the stainless just as an example.

One thing I really dont understand is SS brewtech telling customers to use starsan for this process. I even read something from spike saying it wasn't necessary.

The information provided by Bilsch all makes sense but if you are cleaning gear as often as most should would a build up of iron really become an issue?

For my my equipment I clean with pbw every batch and take apart my valves and deep clean every batch.

Every second batch I take it all apart every last pice inspect clean.

The only issues I have seen was my old gas burner causing the stainless to turn cool colors. It would go away once I cleaned it and used starsan for passivation and I know that's not the correct type of acid.

 

[specialkayme]

As you can get away with not doing it.

I'm no chemist, but I can share my own personal story. I bought a Spike custom kettle about 18 months ago. After every brew I'd wash the kettle out (and all accessories) with a soft sponge and dish soap. Every other brew I'd soak everything in PBW. I never applied an acid or repassified purposefully (never routinely used BKF, or soak in star san) as I thought it was unnecessary.

Last week I drained the kettle, the insides looked like a rainbow. It looked absolutely horrible. Not like a light tint of a rainbow. It looked like a mood ring on drugs.

I read up on the issue, and gave a good scrub with BKF, and it went away (took a good scrub though). I'm hoping the oxalic acid in BKF will repassivate the kettle, but we'll see.

I have no idea if it has to do with inferior SS or not (I will note that my kettle showed some rust spots on the rolled edge that I have to buff out every month or so with some BKF, per the suggestion of Spike). All I know is I thought passivation was a myth . . . until I had to do it.

 

[Jtvann]

My theory on this, is that it may or may not be needed. Some suggest to do it, some suggest it's not needed. Some suggest starsan, some suggest starsan wont work.

I spent a lot of money on my unitank. I cant see every square inch of the inside of it clearly every time I open it up. Passivation with citric acid seemed to be the one agreed upon way to work with correct concentration. Other methods were arguable. It wasnt that expensive to mix up a batch and let it sit. Necessary? Who knows. It was worth a few bucks for piece of mind just on case.

I dont passivate any of my other brewing equipment. Reason why? It wasnt as expensive to replace and I can see it all clearly. May never happen.

 

[Dland]

I'm pretty sure this does not pertain to original post, as their inquiry seems to be answered in subsequent posts:

Since a couple people mentioned the caustic step in cleaning sanitizing (as in PBW) but not the acid step (such as Starsan), I wondered if that could lead to potential discoloration issues. My simplistic understanding is that since the caustic step "opens up" the stainless, the acid step was good to "close" it by way of mild passivation, besides being the sanitizing step.

The only time I felt I should go further in passivation is when I welded and soldered fittings to my keggles, due to high heat involved.

 

[Bobby_M]

Facts: There is iron in stainless steel alloys. Heating stainless steel, as happens in forming and welding finished components, causes the shielding oxide layer to get damaged exposing iron. Surface iron will then impede formation of a pure chromium oxide layer. Iron can then leech into your beer and in worst case you get visible surface rust.

To ponder it a bit more, at least if you see surface rusting you'd know you have a problem. Maybe it's worse when you have mild iron exposed that taints your beer and you can't figure out where the metallic flavor is coming from.

The idea that stainless passivates itself I think comes from the fact that chromium in the alloy does turn to oxide naturally in air, but not when there's a bunch of iron/iron oxide in the way.

 

[Bilsch]

It wouldn't say I'm I'm trying to be controversial. But the more I looked into it the more I noticed it's not white and black. As you can get away with not doing it. I never read a post of someone asking why a beer didn't last on the shelf for 5 months and it end up being the stainless just as an example.

One thing I really dont understand is SS brewtech telling customers to use starsan for this process. I even read something from spike saying it wasn't necessary.

*Warning the following contains LoDo content*

RPH Guy was right on the money in his post above about the iron catalyzing Fenton reactions that speed up the staling in your beer. This loss of freshness is most noticed by those who practice low oxygen brewing and not as big a deal to those who brew the regular way. But again passivation is mostly about creating the proper surface chemistry to help your gear last a good long time in service.

This thing that Spike was trying to get across was that the phosphoric acid in starsan has no effect on stripping the iron from stainless. My personal opinion where SS Brewtech got this idea was confusion with another 5 Star Chemical product called Acid cleaner #5 which along with the phosphoric also contains nitric acid that will in fact passivate stainless.

 

[Jako]

Thank you all for the constructive feedback.

*Warning the following contains LoDo content*

RPH Guy was right on the money in his post above about the iron catalyzing Fenton reactions that speed up the staling in your beer. This loss of freshness is most noticed by those who practice low oxygen brewing and not as big a deal to those who brew the regular way. But again passivation is mostly about creating the proper surface chemistry to help your gear last a good long time in service.

This thing that Spike was trying to get across was that the phosphoric acid in starsan has no effect on stripping the iron from stainless. My personal opinion where SS Brewtech got this idea was confusion with another 5 Star Chemical product called Acid cleaner #5 which along with the phosphoric also contains nitric acid that will in fact passivate stainless.

The acid cleaner #5 worth buying? The talking point of expensive gear and cheap security is not a bad point.

Or would just using BKF Periodically and it naturally passionate a better more simple option

At this point I am looking to simplify my process and cleaning procedures. I have more gear than ever to clean and it's all twice the size as I had before. Also brewing inside creates more cleaning as I cant hose it all down.

 

[Bilsch]

Thank you all for the constructive feedback.
The acid cleaner #5 worth buying? The talking point of expensive gear and cheap security is not a bad point.

Nope. Citric works better and is cheaper.

 

[Jayjay1976]

The down side of using BKF for routinely passivating SS surfaces is that it tends to leave behind a chalky residue if not wiped down during rinsing with a sponge or cloth. An easy rinsing method of applying acid to stainless would save that extra step.

 

[Jtvann]

BKF is very hard to apply evenly to ask surface areas. I wouldn't wasnt to even think about trying it. Submersion in water I'd the best way to evenly boot all concerned surfaces. Toss in some cheap citric acid with heat and you're done.

 

[passedpawn]

Nope. Citric works better and is cheaper.

Plus it's great for cleaning mineral deposits out of coffee pots. (and can be used to make mozzarella cheese from milk).

I've also used it to acidify my mashes.

 

[SanPancho]

As noted above it’s not a myth. It’s just way overblown.
Most reputable sellers make sure it’s done by manufacturer. Unless it’s a custom job or something.

But considering the ridiculous money paid to these places for ss gear you’d think they’d give it to you passivated already.....

 

[jplowe]

I just purchased a Anvil Foundry and SS brewtech bucket, will star san work for passification? I hear it works and then it doesn't work. I hear it's necessary and it's not necessary. Is it really necessary before use? Not trolling, just concerned before starting my brew session this weekend.

 

[RPh_Guy]

will star san work for passification?

Nope. (see above)

Is it really necessary before use?

Necessary? No.
Helpful? Possibly.

 

[Jako]

I just purchased a Anvil Foundry and SS brewtech bucket, will star san work for passification? I hear it works and then it doesn't work. I hear it's necessary and it's not necessary. Is it really necessary before use? Not trolling, just concerned before starting my brew session this weekend.

TSP bath and bar keepers friend better then nothing. My kettles are looking great now.

 

[Die_Beerery]

The down side of using BKF for routinely passivating SS surfaces is that it tends to leave behind a chalky residue if not wiped down during rinsing with a sponge or cloth. An easy rinsing method of applying acid to stainless would save that extra step.

The downside is that it does nothing to passivate SS.

 

[Jayjay1976]

The downside is that it does nothing to passivate SS.

BKF does not passivate stainless? Are you sure?

 

[Die_Beerery]

BKF does not passivate stainless? Are you sure?

Does it contain Nitric or Citric acid?

Post #4.

 

[specialkayme]

Does it contain Nitric or Citric acid?

Post #4.

It contains Oxalic acid.

"To passivate stainless steel at home without using a nitric acid bath, you need to clean the surface of all dirt, oils and oxides. The best way to do this is to use an oxalic acid based cleanser "
https://spaco.org/Passivate.htm#:~:...nless steel at,non-metallic green scrubby pad.
http://howtobrew.com/book/appendices/appendix-b/passivating-stainless-steel
Or
"While . . . Bar Keeper's Friend (Do not apply to electrically etched markings), which is oxalic acid, does work to passivate stainless steel "
https://ssbrewtech.zendesk.com/hc/e...at-acids-can-I-use-to-passivate-my-Stainless-

 

[NewJersey]

I've read a million threads about this on here and a lot of in depth info from metallurgical experts... I've never bothered passivating. I clean new stuff when I get it keep it clean. I have BKF and use it occasionally.
I have some one piece SS steak knives (cheaper henkl) and they get some surface rust spots when they come out of the dishwasher. I wash them all with BKF by hand and then they're good again for awhile.
That's all the science I need personally.

 

[Die_Beerery]

It contains Oxalic acid.

Yes, I know. It was a rhetorical question. My fault for not being more clear. Thanks for your post, however NASA or the ASTM does not recognize oxalic acid as a SS pacification method. Since they send people to space, I believe them over websites created in the 80's, or others.
http://www.********************/wp-...l-treatments-for-stainless-steel-parts.-1.pdf

Cheers.

 

[specialkayme]

. . . Or John Palmer

But whatever. Put your faith in what you read on a forum about what NASA does if that's what moves you. Or Google "times NASA was wrong."

Last I checked, your kettle wasn't sending anyone into orbit.

 

[Die_Beerery]

. . . Or John Palmer

You can continue to list off any folks you like, I can promise you unless its ASTM or NASA, I will not be agreeing.

 

[Yooper]

. . . Or John Palmer

Pshaw. Some random metallurgist from some little engineering school for geeks in the UP of Michigan, who is an honorary Yooper because of living in the UP for those years..........like Palmer knows about stainless passivation just because he's a chemical metallurgist. What could he possible know about such things???????????

 

[Die_Beerery]

Pshaw. Some random metallurgist from some little engineering school for geeks in the UP of Michigan, who is an honorary Yooper because of living in the UP for those years..........like Palmer knows about stainless passivation just because he's a chemical metallurgist. What could he possible know about such things???????????

How many folks has he sent to the moon again?

 

[specialkayme]

How many folks has he sent to the moon again?

How many have you?

 

[Die_Beerery]

How many have you?

I'm not sure why you are fighting with me. I am just listing facts.

I urge you to read the link I posted about the literal standards.

OH! and

 

[Bilsch]

Stellar Solutions, a company that makes industrial passivation chemicals, has this to say about oxalic acid and passivation. Interestingly enough the article focuses on brewery applications.

"A common misconception in the brewing industry is that passivation can be done with any acid. Many brewers have an oxalic acid, phosphoric acid, and/or abrasive based cleaner handy and think that it can be also used to passivate their stainless steel. While these cleaners do help bring the stainless steel surface down to bare metal, they do not selectively remove iron, and so the metal surface created will still have a very high percentage of iron. The chromium on the surface will passivate into chromium oxide, but without a correct acid treatment, that chromium only covers at most 20% of the surface. Passivation standards like ASTM A967 do not recognize these acids for the purpose of passivating stainless steel."

http://citrisurf.com/brewery-winery-distillery-passivation/

 

[Jayjay1976]

hsa rears its ugly head once more.

 

[Bilsch]

hsa rears its ugly head once more.

It's like the plague.. you never know where it will pop up and it will kill you.
Ok, I made that last part up.

 

[specialkayme]

It's like the plague..

Too soon man.