Stainless Passivation

[MX1]

Looking to make sure I have the math right, but my plan is to add about 2 tablespoons of Citric acid per gallon of water to get just above a 5% solution to use in my new kettle and fermenter.

Sound right?

I have read that stars can be used but at 1oz per gallon, that cost way to much..

Also, can I reuse the solution? If I start in fermentor, then rack it over to the brew kettle will that be ok? Will it damage my hoses?

Tim

 

[Rev2010]

Never used Citric Acid, only ever used StarSan, so can't answer that one, but yes you can reuse the solution and no it won't damage your tubing, just rinse them with water after the transfer..


Rev.

 

[Nokt]

What about Bar Keepers Friend?

 

[schematix]

Hot citric acid is amazing. I did 10% at 180F. If you do it right your resulting water will be bright green or orange. You can reuse the heck out of the solution.

Starsan and BKF don’t really passivate.

Also you can buy a 5lb bag of citric acid for a little over $10 on amazon.

 

[Cavpilot2000]

Hot citric acid is amazing. I did 10% at 180F. If you do it right your resulting water will be bright green or orange. You can reuse the heck out of the solution.

Starsan and BKF don’t really passivate.

Also you can buy a 5lb bag of citric acid for a little over $10 on amazon.

WHat he said.
Plus, BKF leaves residue that has to be washed off more aggressively than simply rinsing, which is fine for a kettle, but not so good for valves, fittings, and stuff with surfaces you can't wipe off.

 

[MX1]

How did you measure out your solution

 

[MaxStout]

Interesting about Starsan not being effective. The instructions for the Brewbucket I bought called for 1oz/gallon Starsan. Took almost half the damn bottle of Starsan for this.

I haven't used the BB yet, might try the citric method first.

 

[Rev2010]

Interesting about Starsan not being effective. The instructions for the Brewbucket I bought called for 1oz/gallon Starsan.

Not sure I believe the comment that it doesn't really passivate as Phosphoric Acid, which is the highest concentration of ingredient in StarSan, is very well known to passivate. Also, at the strength of concentration of 1oz per gallon how could it not? Has worked fine for all my stainless gear.


Rev.

 

[schematix]

How did you measure out your solution

Used sight glass in BK to measure water.
Converted to mass. Used my brewing ingredient scale to measure the citric acid. Easy peasy.

My brewing vessels looking absolutely flawless when complete. I had done the BKF “passivation” on one of the 3 vessels before this one and uh, the color of the resulting water told me all I needed to know about BKF. It does a great job on my stainless sink though.

 

[hedgie57]

I've never passivated.J use kept the very thing clean and haven't had any problems

 

[schematix]

It’s important in low oxygen brewing because iron is a big contributor to Fenton reactions. A poorly passivated vessel has a lot of free surface iron that wort will dissolve into it. Passivating strips it away so a new protective oxide layer can form.

 

[SpikeBrewing]

A lot of misinformation about passivation. We've actually worked with one of the local universities on this topic. See our knowledgebase article which touches on the subject and has a link to a study touching specifically on stainless steel passivation.

https://spikebrewing.freshdesk.com/...-do-i-need-to-passivate-my-kettle-before-use-

 

[MaxStout]

Not sure I believe the comment that it doesn't really passivate as Phosphoric Acid, which is the highest concentration of ingredient in StarSan, is very well known to passivate. Also, at the strength of concentration of 1oz per gallon how could it not? Has worked fine for all my stainless gear.


Rev.

I was skeptical too, but another poster mentioned it and I wanted to investigate it further. It seems to me that a more concentrated solution of Starsan would provide enough acid to remove free-iron deposits. SS Brewtech suggests either Starsan, BKF or citric will work.

Thank you to @SpikeBrewing for the linked information. Maybe we've been over-thinking this.

 

[schematix]

I think the point here is that not all stainless has been perfectly treated before it gets to you. I know I have a dozen fittings with rust on them and they claim to be 304 or 316.

So yah stainless does auto oxidize - in fact you let it air dry after using the chemicals. But that doesn’t mean it isn’t otherwise contaminated or completely free of surface defects.

It’s certainly a process that’s not for everyone.

 

[MX1]

I will still put my gear through the process at the concentration I stated in the OP if for no other reason than cleaning

 

[Cavpilot2000]

I have found that letting a normal concentration of STar-San solution sit for a few days at room temp in my BK will make it bright and fresh-looking.
But citric acid is cheaper and more friendly to work with and, with heat, can do the job in under an hour.

 

[LarMoeCur]

I think the point here is that not all stainless has been perfectly treated before it gets to you. I know I have a dozen fittings with rust on them and they claim to be 304 or 316.

So yah stainless does auto oxidize - in fact you let it air dry after using the chemicals. But that doesn’t mean it isn’t otherwise contaminated or completely free of surface defects.

It’s certainly a process that’s not for everyone.

I’d bet those rust marks are pieces of steel left over from the tooling process. Most fitting parts are cast and then machine finished with steel carbide cutters. Kettles are pressed into steel molds using heat and a hydraulic steel ram. These industrial processes can leave carbide/steel pieces embedded in surface of the stainless. Those impurities may not immediately rust but over time will start to show. A good acid bath should dissolve those less hard/acid resistant pieces of non-stainless. Clean stainless will instantly passivate when exposed to oxygen.

 

[Bilsch]

Not sure I believe the comment that it doesn't really passivate as Phosphoric Acid, which is the highest concentration of ingredient in StarSan, is very well known to passivate.
Rev.

Where did you find the very well known sources that state phosphoric acid will passivate, i.e. remove iron and enrich the chromium layer? Because I can find no incidences in the metal finishing industry where H3PO4 is used for this purpose. It is sometimes used as a pickle but that's a different process.

While this idea keeps popping up on homebrew sites, the reality is that Starsan (phosphoric acid) does not passivate stainless.

 

[Rev2010]

Where did you find the very well known sources that state phosphoric acid will passivate.

I don't keep a log of all the sources I've read from when I initially was looking to passivate stainless years ago. But a simple Google search yields this as an top result example:

https://www.bssa.org.uk/topics.php?article=32

"Phosphoric acid is used as a chemical-cleaning agent for stainless steels.
It is used in commercially available stainless steel cleaning preparations and so if used in accordance with the manufacturers / suppliers instructions will not etch or corrode the steel surface.
Phosphoric acid is not considered to be a 'passivating' acid but the clean surface left after treatment should allow the stainless steel to naturally self passivate."

Also the came up which included Phosphoric in the test: http://astropak.com/wp-content/uploads/2015/01/Comparison-Of-Passivation-Modalities.pdf

"Conclusion
All three passivation modalities provided enhanced corrosion resistance on the 304L stainless
steel test coupons. The citric acid passivation proved to be the most efficacious surface
treatment tested"

Whether it's right or wrong I don't seem to have any issues with my stainless equipment that I used StarSan in high concentration with.


Rev.

 

[Bilsch]

My problem is that your initial post makes it sound as if phosphoric is commonly used at a passivating acid. These two links are hardly constitute "well known" in the industry. One even says quite clearly that phosphoric is not considered a passivating acid. Used as a cleaning acid certainly, but as I said is not used in the metal finishing industry for passivation. There is a reason no one uses it.

 

[MX1]

My problem is that your initial post makes it sound as if phosphoric is commonly used at a passivating acid. These two links are hardly constitute "well known" in the industry. One even says quite clearly that phosphoric is not considered a passivating acid. Used as a cleaning acid certainly, but as I said is not used in the metal finishing industry for passivation. There is a reason no one uses it.

Well the team at SS Brew Tech seem to think Starsan can be used to passivate it.....

and this thread is not about Starsan, it is about the amount of CA I plan to use

 

[Bilsch]

Use 4% citric at 160f to 180f for an hour or two.

 

[Gadjobrinus]

I was very surprised to find one of my vessel's inside bottom hit pretty heavily with rust one morning. I was concerned I was making a bonehead move by keeping them on my mild steel (and rusting, by design, really) frame. But even to my inept-technically mind, it seemed weird the oxidation would move through the metal from the ss contact with the stainless. Never had this issue before. Not knowing other methods (actually, never had the need with other builds, either), I used BKF and rinsed off like crazy.

Perhaps I'm blowing it by keeping the vessels on the frame? I always hot rinse, wash with PBW after a session, rinse again (all through a pumped recirc), and carefully dry the vessels, FWIW.

 

[MX1]

I was very surprised to find one of my vessel's inside bottom hit pretty heavily with rust one morning. I was concerned I was making a bonehead move by keeping them on my mild steel (and rusting, by design, really) frame. But even to my inept-technically mind, it seemed weird the oxidation would move through the metal from the ss contact with the stainless. Never had this issue before. Not knowing other methods (actually, never had the need with other builds, either), I used BKF and rinsed off like crazy.

Perhaps I'm blowing it by keeping the vessels on the frame? I always hot rinse, wash with PBW after a session, rinse again (all through a pumped recirc), and carefully dry the vessels, FWIW.

has it rusted again after BKF?

 

[Gadjobrinus]

has it rusted again after BKF?

No - or at least I think not. Kind of sucks, but we had to move and my brewery is at a garage my friend is lending me, so far without water, though there is electrical. All my lab/propagation stuff is here at home. So cannot easily get over there as often to see the vessel condition. Hope not! Had never seen rust like this on s/s, before, so I guess I was broadsided a bit.

 

[augiedoggy]

I have a stainless meat slicer we bought for our brewpub at an auction that has rusted spots starting all over (my guess is someone used steel wool). I tried BKF twice and even left a film of it and the rust still comes back. I will try citric acid next.

it did always seem to work on my brewing kettles though.

 

[Cavpilot2000]

Looking to make sure I have the math right, but my plan is to add about 2 tablespoons of Citric acid per gallon of water to get just above a 5% solution to use in my new kettle and fermenter.

Sound right?

Tim

Not sure about 2T/gal.
5% is around 6.5 oz.
Not sure how much a T of citric weighs, but I don't think 2T will get 6.5 oz.
I made 10 gallons of 5% yesterday which, unless my math is way off, was 4 lb of citric acid.

 

[MX1]

maybe your right, but it seemed to work out, it was really just another step in the cleaning process.
SS really does not need to be passivated at our level (IMHO) but every little bit helps

 

[Cavpilot2000]

maybe your right, but it seemed to work out, it was really just another step in the cleaning process.
SS really does not need to be passivated at our level (IMHO) but every little bit helps

I also question whether the heat is necessary for the process, but rather speeds the process. I strongly suspect that a room temp soak for, say, 24-48 hours, will do the same thing.

 

[Bilsch]

I think there were some charts in the NASA write up with temperature as a variable. My take on it was to use heat.

 

[Bilsch]

SS really does not need to be passivated at our level (IMHO) but every little bit helps

It depends on if your concerned about accelerated staling and the loss of fresh malt flavors from Fe catalyzed fenton reactions. Some brewers 'at our level' are very much worried about this and proper passivation is a great way to reduce the free iron on the surface of your stainless equipment. It also of course improves the corrosion resistance.

 

[brew703]

maybe your right, but it seemed to work out, it was really just another step in the cleaning process.
SS really does not need to be passivated at our level (IMHO) but every little bit helps

My Brew Bucket will arrive tomorrow and I'm thinking about using CA to passivate. As you mentioned the instructions state to use TSP to clean and Starsan to passivate. I don't want to use all my starsan for this so I'm planning to use CA at a rate of 5.32 oz/gal heated to 160 degrees for 30 minutes I think. This is for 4% solution.

Since this thread is a month old I assume you already did the passivation. How did it come out using CA? Did you use 2T per gallon as mentioned in your original post?

 

[MX1]

I did....you could tell it did something because it got a green tint to it.....

I just finished up my first brew with the bucket....all the little things that went wrong were my fault, getting used to a new way of transferring....find a way to clamp the hose to the valve.....just sayin'...lol

Clean up was simple and easy, and the beer racked off well, leaving the cake behind....

 

[brew703]

Did the hose come loose off the valve due to pressure or something else? I transfer from my kettle to my carboy using a 3 pc valve and silicon tube and never had it slip off. It fits kinda snug and don't think it would fall off even it was hit. Just curious what may have happened with yours. I do have some worm clamps I could use just in case. Did you transfer under pressure or used gravity? My issue with the SSBT and Anvil is the valve. Always worry about it leaking but seems like there it's a non issue.

I almost went with the portless Chapman and was going to modify the lid to accept a SS racking cane, add a gas port and rack to my keg that way. What swayed me was the fact I can eventually get the cooling coils with the SSBT. I'll probably go that route next year if my man cave is up and running.

I wanted a SS fermenter mainly for ease of cleaning and be able to DH in a bag. I wish the SSBT could accept a bit more pressure than 1-3 lbs but I should be ok with that. Just couldn't justify the cost of a Spike or SSBT conical or Unitank plus having to purchase a glycol chiller or make one.

As for as the CA is concerned, not sure what 2T weighs but I guess I can see how close it comes to 5.32 oz.

 

[Rev2010]

.find a way to clamp the hose to the valve.....just sayin'...lol

3/8" tubing doesn't work well on the valve as they made the barbs smoother than usual to "preserve" people's tubing - at least that's what they told me in an email. Anyhow, I went with 1/4" tubing and it holds on perfectly.


Rev.

 

[MX1]

Did the hose come loose off the valve due to pressure or something else? I transfer from my kettle to my carboy using a 3 pc valve and silicon tube and never had it slip off. It fits kinda snug and don't think it would fall off even it was hit. Just curious what may have happened with yours. I do have some worm clamps I could use just in case. Did you transfer under pressure or used gravity? My issue with the SSBT and Anvil is the valve. Always worry about it leaking but seems like there it's a non issue.

I almost went with the portless Chapman and was going to modify the lid to accept a SS racking cane, add a gas port and rack to my keg that way. What swayed me was the fact I can eventually get the cooling coils with the SSBT. I'll probably go that route next year if my man cave is up and running.

I wanted a SS fermenter mainly for ease of cleaning and be able to DH in a bag. I wish the SSBT could accept a bit more pressure than 1-3 lbs but I should be ok with that. Just couldn't justify the cost of a Spike or SSBT conical or Unitank plus having to purchase a glycol chiller or make one.

As for as the CA is concerned, not sure what 2T weighs but I guess I can see how close it comes to 5.32 oz.

3/8 tubing was a bit loose....came off under gravity feed....but I was on top of the valve and turned it off.
I think leaking is a non issue with the valve, it is well designed, you should see what I mean when you get yours.
I did not dry hop this batch, but clean up was super simple....it is everything I love about a simple bucket, and none of the things I hate.....about a simple bucket...lol.

For this batch, i think i could have left the racking cane in the down position and been good to go.
Boiled up a quart mason jar and saved the slurry...first time for that....

T

 

[brew703]

Received my fermenter yesterday. Much nicer than the Anvil I sent back. I do have 3/8" silicon tubing so that will have to work. I have some clamps I can use for safety.
I sent an email to SSBT about passivation and was told citric acid is suitable to use in place of starsan. So will do that tomorrow as tonight will be dedicated to cleaning.

What position do you guys leave the racking arm during fermentation? I would think in the downward position.

 

[MX1]

I left it down...

Think I am going to to get a Teflon washer to install on the inside of the racking arm/valve to make it easier to rotate

 

[brew703]

I left it down...

Think I am going to to get a Teflon washer to install on the inside of the racking arm/valve to make it easier to rotate

Seems like someone put a washer on the inside and it caused the valve to leak. Let us know if it works.
Just finished cleaning with TSP/90. The inside didn't seem to have any residue before and it's clean now.
Getting ready to hit it with some CA.

 

[Rev2010]

I think I am going to to get a Teflon washer to install on the inside of the racking arm/valve to make it easier to rotate

Why bother? I just use my mash spoon (rinsed and sanitized) to gently push it down when it gets down to the arm. That said, I have left it down by accident many times and it's never been an issue. Not sure I really notice any difference between leaving it sideways or down.


Rev.