Passivation using citric acid

Discussion in 'General Brewing Discussions' started by Nola_Brew, Jun 20, 2020.

  1. Nola_Brew

    Nola_Brew Active Member

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    I have a 10.5 gal bayou classic kettle. It was purchased used as part of an electric set up.

    I'm not sure if the previous owner passivated the kettle.
    My issue is what appears to be beer scale build up. It takes a lot of time to clean but I have not been able to 100% remove. I'm thinking passivating might help prevent the build up.

    Directions on the web show 4-10% solution. I am having a hard time trying to figure out how much citric acid to use for 10 gal if water.

    I've read numerous posts but I cannot figure out how much to use.
    Can someone help to determine the amount?
     
  2. Semper Sitientem

    Semper Sitientem Well-Known Member

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    I saw a post with pictures that showed great results (if true). They used 3 teaspoons per half gallon of water. With 10 gallons that would be 1.25 cups of citric acid.

    Also, just to mention, I use a Five Star product call “BS Remover” that works great. Soak for 10 minutes and it dissolves everything. I don’t fill my kettle all the way. Just dilute enough according to the directions to make sure the bottom is covered and wet the sides.
     
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  3. thunderwagn

    thunderwagn Well-Known Member

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    I also use the 5 Star BS Remover. Great product for sure.
     
  4. Nola_Brew

    Nola_Brew Active Member

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    Will have to see if I can find the Five Star BS remover.
    Thanks for the info.
     
  5. Nosybear

    Nosybear Well-Known Member

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    If you don't see rust, it's passivated. They come from the factory passivated and unless you do something pretty extreme, they stay passivated. You likely need to do absolutely nothing.
     
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  6. Nola_Brew

    Nola_Brew Active Member

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    I took some BKF and made a paste. Let it dry then rinsed. It removed the scale that has been forming about every other brew. I've never had that with my previous kettle so unsure why it's happening with this one.
     
  7. Nosybear

    Nosybear Well-Known Member

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    Whatever the cause, it's not the kettle. I believe BKF is alkaline, the exact opposite of what's needed to passivate stainless. Could be a change in the municipal water - if you have lead pipes down there, the water department is likely making your water very alkaline to keep from dissolving the lead - could be a cause. They do it in Denver because of old connections from the city's mains to houses.
     
  8. Nosybear

    Nosybear Well-Known Member

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    Occurred to me after I'd clicked away: Have you considered beerstone (calcium oxalate) or some other calcium precipitate as the cause of the scale (it generally is when hard water is boiled).
     
  9. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    Bar Keepers Friend is the cheapest and best choice for both beer stone and passivating. BKF has an acid in it the passivates and attacks beer stone. BS remover works good for things your can’t scrub. If you you can scrub it, BKF is the best bet. After cleaning it with BKF, leave it set for several days and it will passivate. Citric acid passivates but doesn’t remove beer stone. Like Nosy said, it probably doesn’t need to be passivated, but it you clean regularly with BKF, you don’t have anything to worry about.
     
  10. Nola_Brew

    Nola_Brew Active Member

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    After a brew day I usually rinse the kettle then rub the inside with BKF then rinse. after that it gets an oxy soak at 165 that gets circulated thru my pump for 10-20 min. I never had this issue before.

    Nosy, no lead pipes here. I use RO water for every brew and have been for 5 yrs.
     
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  11. The Beerery

    The Beerery Active Member

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    I hate to be this guy, but. The only things that passivate SS are citric and nitric acid. If you don't believe me, just ask NASA.
     
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  12. thunderwagn

    thunderwagn Well-Known Member

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    5 Star BS Remover cleans and, if allowed to air dry passivates. Can't speak for BKF, but the 5 Star product works excellent. 5 Star has a pretty solid reputation on a pro and homebrew level, but I've never heard anything negative about BKF either. I'm just not certain it's going to be removing what you need it to.
     
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  13. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    That is correct. It's often said and I repeated it, that oxalic acid in Bar Keeper Friend would passivate the stainless. It will renew the shine, but it doesn't necessarily mean it's passivated, it may have not ever needed to be passivated to begin with.

    Passivating stainless removes the free iron from the surface of the stainless steel so the chromium can be exposed to oxygen, thus creating a very thin layer of chromium oxide. This protects the iron in stainless from reacting to oxygen and producing rust or iron oxide.

    The only time you really need to passivate is after the stainless was welded, brazed, machined, drilled or heated above 1000 F or so. If the stainless ever got red hot, it lost it's passivation. If it forms rust, it needs to be scrubbed clean and treated with either citric (preferred) or nitric acid.

    To this day there is a lot of debate about how to passivate stainless. It can happen naturally to clean stainless when exposed to air for a long period of time. But the only way that has been proven and accepted is to passivate the stainless with nitric acid or citric acid. The stainless must be exposed to the air (and dry) for 24-48 hours after the treatment to allow the chromium oxide to form.

    You can pick up citric acid at Walmart or any other store that has canning supplies. It's used to drop the pH in tomatoes when canning them with a hot water bath.
     
  14. Hawkbox

    Hawkbox Well-Known Member

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    So I'm planning to drill some holes in my kettle and I was wondering, do I need to have it soak in the acid for a length of time or could I just spray a coating on after I clean it and let it dry that way?
     
  15. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    The SS can be passivated in 4 minutes at 170F with a 4-10% citric acid concentration by weight. As the temperature goes down it takes longer. I think if you had a spray bottle with a citric acid mixture, you could spray it , let set and spray it again later to make sure it took. It takes 40-60 minutes at room temperature to passivate with citric acid. Wipe it dry and let it set for 24-48 hours and you should be good.

    if you can bath it for 60 minutes, that would be best, but it may not be all that easy in some cases.
     
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  16. Hawkbox

    Hawkbox Well-Known Member

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    Gotcha. I have a wash tub I could fill up past the holes I'm planning to drill so that would be doable, just need to track down citric acid to get that concentration.
     
  17. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    The nice thing about citric acid is that any place that sells canning ingredients has it. I got it at Walmart.
     
  18. Nola_Brew

    Nola_Brew Active Member

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    The problem I have with citric acid is trying to determine how much to use. There is no clear answer. There are different amounts all over the web.

    It would be nice to have one post that will show x amt of citric is needed per gallon to obtain a 4% solution and all the way up to 10%. I just gave up trying to figure it out.

    Also, I suggested passivating because I never had beer scale in my other kettle so something is causing it to form in the bayou classic. Not sure if it's cheaper stainless being used or something else. I just don't want to scrub and deal with it every time I brew. My brew days used to be 4 - 5 hours. hrs from start to finish. Now an extra hour is added due to recirculating oxy through my pump and hoses, then repeat the process with clean water. Then if I have to deal with beer scale that's more time.
     
  19. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    Beer scale or stone is a mixture of calcium deposits and protein, most acids cannot remove them by themselves, they have trouble with the protein that gets in the way of the acid dissolving the calcium. It’s a natural product of brewing, especially if your brewing with hard water. The stainless steel really doesn’t make any difference in its formation.

    I have Ball brand citric acid that contains 98% citric acid, so adding 8 ounces of acid to one gallon will give about a 6% citric acid solution.

    Most farm supply stores carry milk stone remover for dairy operations. Milk stone and beer stone are very similar. I can get a gallon for about 12 bucks. It’s cheaper than BS remover. It’s made from phosphoric acid for the calcium and a surfactant for the protein. It seems to work pretty well.
     
  20. Trialben

    Trialben Well-Known Member

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    Is this beer stone that tan brown build up on the bottom (usually) of the kettle.

    I find a soak in hot Sodium perc and a bit of a scrub with steal wool brings it up noice and shiny shiny.

    Learning alot from this thread...
     
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