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General Category => General Homebrew Discussion => Topic started by: trapae on June 21, 2020, 06:21:41 PM

Title: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: trapae on June 21, 2020, 06:21:41 PM
A while ago I had a beer that after while started tasting funny, like a little bit too sweet. Not sure if it was bad or not. The keg I used with that beer, I noticed had two small reddish rust color spots in the very bottom. Not sure if they were two spots of rust or beer stone. I Cleaned the keg with my key cleaner using PBW, And then sanitized it. Looked in and those two little spots were still there. Then I soaked it in PBW overnight and still there. Most recently I put beer stone remover near 100% strength and layered the bottom of the keg with it for several hours and then put my arm down there with a scrubber and scrubbed and it’s still there. Left the beer stone remover in it overnight and those two spots are still there. Not sure if these spots are beer stone or two little spots of rust and if it could possibly be a source of ongoing infection.? Any ideas?  I’m worried to put another beer in the keg now.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: denny on June 21, 2020, 06:49:31 PM
Try Barkeeper's Friend.  Good chance it will remove the spots and repassivate the SS.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: ynotbrusum on June 22, 2020, 10:53:07 AM
You might need an extended period of soaking.  I have soaked kegs a week to remove beerstone, which for me was more of a whitish scaly looking deposit.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: goose on June 22, 2020, 12:34:23 PM
An acid wash will remove beer stone.  I got some from a dairy supply store but you can also soak with a solution of Star San at a concentration of 1 oz. per gallon of water and see if that removes them.  The acid soak will also re-passivate the stainless steel.

Barkeepers Friend is oxlaic acid and would also work.  the problem is scrubbing it on the bottom of the keg and I do not know the ratio of the powder to water for uusing it as a soak (Denny?).  When I have used it on my keggles, I put it on a damp Dobie pad, scrub the stainless with it, and allow ity to sit on the stainless for about 5 minutes before rinsing it off.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: BrewBama on June 22, 2020, 12:49:05 PM
An acid wash will remove beer stone.  I got some from a dairy supply store ...

$15 at a Tractor Supply. It’s good stuff.

https://www.tractorsupply.com/tsc/product/dairyland-sterosol-milkstone-remover-acid-rinse


Sent from my iPad using Tapatalk
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 22, 2020, 01:46:04 PM
This is timely because I just started getting medieval on my kegs.  My water is on the hard side and beerstone or just hard water deposits will accumulate.  I have not seen 'red'... for me it's white and rough like sandpaper.  If what you're seeing is beerstone, something acidic should work... like Starsan.  What I have been doing is cleaning the keg out with the hose and then dropping 5 tbsp of LD Carlson EasyClean in there.  I find it to be much more effective than Oxi or PBW.  Then I boil 5 gallons of water and add that to the keg using a funnel and I leave it overnight.  I dump it out and then reach into the keg (I'm not exactly Mr. Universe) with some plain steel wool and scrub anything that seems to still be there.  It comes off easily.  I have 10 kegs and I have done this now on 4 of them.  When done, the insides of these kegs sparkle as if they were brand new.  I have also taken the pressure washer to a couple that needed some extra punishment.  If it's rust you're seeing, I might retire that keg.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: denny on June 22, 2020, 02:06:06 PM
An acid wash will remove beer stone.  I got some from a dairy supply store but you can also soak with a solution of Star San at a concentration of 1 oz. per gallon of water and see if that removes them.  The acid soak will also re-passivate the stainless steel.

Barkeepers Friend is oxlaic acid and would also work.  the problem is scrubbing it on the bottom of the keg and I do not know the ratio of the powder to water for uusing it as a soak (Denny?).  When I have used it on my keggles, I put it on a damp Dobie pad, scrub the stainless with it, and allow ity to sit on the stainless for about 5 minutes before rinsing it off.

You can't really use BKF as a soak.  You need to scrub.  I have a long handled brush I use for scrubbing the bottom of kegs.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: denny on June 22, 2020, 02:06:52 PM
This is timely because I just started getting medieval on my kegs.  My water is on the hard side and beerstone or just hard water deposits will accumulate.  I have not seen 'red'... for me it's white and rough like sandpaper.  If what you're seeing is beerstone, something acidic should work... like Starsan.  What I have been doing is cleaning the keg out with the hose and then dropping 5 tbsp of LD Carlson EasyClean in there.  I find it to be much more effective than Oxi or PBW.  Then I boil 5 gallons of water and add that to the keg using a funnel and I leave it overnight.  I dump it out and then reach into the keg (I'm not exactly Mr. Universe) with some plain steel wool and scrub anything that seems to still be there.  It comes off easily.  I have 10 kegs and I have done this now on 4 of them.  When done, the insides of these kegs sparkle as if they were brand new.  I have also taken the pressure washer to a couple that needed some extra punishment.  If it's rust you're seeing, I might retire that keg.

Try Craftmeister Alkaline and hot water.  That stuff will clean anything.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 22, 2020, 02:19:17 PM
This is timely because I just started getting medieval on my kegs.  My water is on the hard side and beerstone or just hard water deposits will accumulate.  I have not seen 'red'... for me it's white and rough like sandpaper.  If what you're seeing is beerstone, something acidic should work... like Starsan.  What I have been doing is cleaning the keg out with the hose and then dropping 5 tbsp of LD Carlson EasyClean in there.  I find it to be much more effective than Oxi or PBW.  Then I boil 5 gallons of water and add that to the keg using a funnel and I leave it overnight.  I dump it out and then reach into the keg (I'm not exactly Mr. Universe) with some plain steel wool and scrub anything that seems to still be there.  It comes off easily.  I have 10 kegs and I have done this now on 4 of them.  When done, the insides of these kegs sparkle as if they were brand new.  I have also taken the pressure washer to a couple that needed some extra punishment.  If it's rust you're seeing, I might retire that keg.

Try Craftmeister Alkaline and hot water.  That stuff will clean anything.
I mentioned elsewhere that I used EasyClean years ago and I noticed that it removed things that other cleansers didn't seem to.  There were also warnings on the container about using impervious gloves and safety goggles when you handled it... which seemed a little scary.  Those warnings are no longer on the packaging but it still cleans very well.  I had a cobra tap with tubing that looked stained.  I tried using Oxi with hot water and PBW as well without luck.  I filled the sink with hot water and EasyClean and started a siphon into a bucket on the floor.  I watched as amber-colored flakes started coming off the inside walls of the tubing.  After 15-20 minutes of that the tubing looked brand new.  The guys on The Biergarten compared the ingredients to PBW and declared them the same but there is something different about EasyClean. 
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: denny on June 22, 2020, 02:43:47 PM
Well, that's why I didn't recommend Oxi or PBW.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 22, 2020, 03:08:44 PM
Well, that's why I didn't recommend Oxi or PBW.
I thought you were an Oxi fan.  For general-purpose cleaning I feel like it's okay.  But if you have a tough cleanup job, I'm not sure it's up to it.  I have always been focused on good sanitation but there are times when I'm looking at other things and I assume my cleaning and sanitation are fine.  A few weeks ago I closely examined an empty keg and noticed I needed to get a little more serious about keg conditions.

As far as the OP goes... if it's beerstone Starsan should absolutely do the trick.  If you use whichever cleanser you prefer plus some boiling water (you don't need much if the spots are on the bottom) and it still doesn't come off, I think I might stop right there.  If you can get your arm all the way in and use some steel wool on the spots, you might learn more about what they really are. 
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: denny on June 22, 2020, 03:18:21 PM
Oxi is OK.  PBW is better. Craftmeister Alkaline kicks both their butts.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 22, 2020, 03:23:42 PM
Oxi is OK.  PBW is better. Craftmeister Alkaline kicks both their butts.
So you use the Craftmeister for general-purpose cleaning or only for tough jobs or what?  I feel like if you used it all the time then there would be no "tough jobs".  :P  I'm digging this EasyClean but I'm always open-minded about good products.  Cheers.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: hopfenundmalz on June 22, 2020, 03:50:38 PM
This is timely because I just started getting medieval on my kegs.  My water is on the hard side and beerstone or just hard water deposits will accumulate.  I have not seen 'red'... for me it's white and rough like sandpaper.  If what you're seeing is beerstone, something acidic should work... like Starsan.  What I have been doing is cleaning the keg out with the hose and then dropping 5 tbsp of LD Carlson EasyClean in there.  I find it to be much more effective than Oxi or PBW.  Then I boil 5 gallons of water and add that to the keg using a funnel and I leave it overnight.  I dump it out and then reach into the keg (I'm not exactly Mr. Universe) with some plain steel wool and scrub anything that seems to still be there.  It comes off easily.  I have 10 kegs and I have done this now on 4 of them.  When done, the insides of these kegs sparkle as if they were brand new.  I have also taken the pressure washer to a couple that needed some extra punishment.  If it's rust you're seeing, I might retire that keg.

Way back when it was said not to use steel wool on Stainless. You can deposit iron from the steel wool onto the stainless.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 22, 2020, 03:54:15 PM
This is timely because I just started getting medieval on my kegs.  My water is on the hard side and beerstone or just hard water deposits will accumulate.  I have not seen 'red'... for me it's white and rough like sandpaper.  If what you're seeing is beerstone, something acidic should work... like Starsan.  What I have been doing is cleaning the keg out with the hose and then dropping 5 tbsp of LD Carlson EasyClean in there.  I find it to be much more effective than Oxi or PBW.  Then I boil 5 gallons of water and add that to the keg using a funnel and I leave it overnight.  I dump it out and then reach into the keg (I'm not exactly Mr. Universe) with some plain steel wool and scrub anything that seems to still be there.  It comes off easily.  I have 10 kegs and I have done this now on 4 of them.  When done, the insides of these kegs sparkle as if they were brand new.  I have also taken the pressure washer to a couple that needed some extra punishment.  If it's rust you're seeing, I might retire that keg.

Way back when it was said not to use steel wool on Stainless. You can deposit iron from the steel wool onto the stainless.
Is that only for kegs or stainless in general?  I have stainless appliances and a stainless cooktop and steel wool was mentioned as the only material to be used to clean it.  My wife occasionally uses a green pad on our cooktop and there are scratches from that.  When I used steel wool on stainless it always cleans beautifully without scratching or discoloring.  I should also mention that this routine of mine is not something I would do EVERY time I had an empty keg.  Just an occasional jolt to my regular cleaning routine.  Thanks for the information.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: hopfenundmalz on June 22, 2020, 04:25:52 PM
This is timely because I just started getting medieval on my kegs.  My water is on the hard side and beerstone or just hard water deposits will accumulate.  I have not seen 'red'... for me it's white and rough like sandpaper.  If what you're seeing is beerstone, something acidic should work... like Starsan.  What I have been doing is cleaning the keg out with the hose and then dropping 5 tbsp of LD Carlson EasyClean in there.  I find it to be much more effective than Oxi or PBW.  Then I boil 5 gallons of water and add that to the keg using a funnel and I leave it overnight.  I dump it out and then reach into the keg (I'm not exactly Mr. Universe) with some plain steel wool and scrub anything that seems to still be there.  It comes off easily.  I have 10 kegs and I have done this now on 4 of them.  When done, the insides of these kegs sparkle as if they were brand new.  I have also taken the pressure washer to a couple that needed some extra punishment.  If it's rust you're seeing, I might retire that keg.

Way back when it was said not to use steel wool on Stainless. You can deposit iron from the steel wool onto the stainless.
Is that only for kegs or stainless in general?  I have stainless appliances and a stainless cooktop and steel wool was mentioned as the only material to be used to clean it.  My wife occasionally uses a green pad on our cooktop and there are scratches from that.  When I used steel wool on stainless it always cleans beautifully without scratching or discoloring.  I should also mention that this routine of mine is not something I would do EVERY time I had an empty keg.  Just an occasional jolt to my regular cleaning routine.  Thanks for the information.

Kegs and fermenters was what they talked about. Iron in you beer, even if you don't taste it, will cause stalling.

Ken Grossman talked about this in Portland IIRC. Sierra Nevada will do more passivation to get iron to lower levels.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: hopfenundmalz on June 22, 2020, 04:33:19 PM
This has a caution against vsteel wool, and a couple of other nice tips.

https://www.probrewer.com/library/used-tanks/the-care-and-feeding-of-stainless-steel/#:~:text=Never%20use%20steel%20wool%2C%20which,their%20beer%20in%20soda%20kegs.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: hopfenundmalz on June 22, 2020, 04:37:59 PM
And John Palmer's $0.02 on it.
http://howtobrew.com/book/appendices/appendix-b/passivating-stainless-steel
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 22, 2020, 04:48:20 PM
Interesting and thanks again.  I will keep an eye on these kegs that I cleaned to see how they hold up.  Since Palmer suggested a green pad instead of steel wool, I feel like I could use that and get the same results without damaging the inside of the keg.

Also... to the OP:  my apologies for the thread-jack.  ;)
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: denny on June 22, 2020, 04:48:58 PM
Oxi is OK.  PBW is better. Craftmeister Alkaline kicks both their butts.
So you use the Craftmeister for general-purpose cleaning or only for tough jobs or what?  I feel like if you used it all the time then there would be no "tough jobs".  :P  I'm digging this EasyClean but I'm always open-minded about good products.  Cheers.

I use Craftmeister Oxygen for "normal" cleaning.  I use the alkaline for rough stuff or if I don't have hot water available.  The Alkaline works better in cold water than PBW works in hot water.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: hopfenundmalz on June 22, 2020, 06:16:56 PM
Interesting and thanks again.  I will keep an eye on these kegs that I cleaned to see how they hold up.  Since Palmer suggested a green pad instead of steel wool, I feel like I could use that and get the same results without damaging the inside of the keg.

Also... to the OP:  my apologies for the thread-jack.  ;)

A few people say the blue or white scubbies are less likely to scratch the stainless.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 22, 2020, 06:37:29 PM
Interesting and thanks again.  I will keep an eye on these kegs that I cleaned to see how they hold up.  Since Palmer suggested a green pad instead of steel wool, I feel like I could use that and get the same results without damaging the inside of the keg.

Also... to the OP:  my apologies for the thread-jack.  ;)

A few people say the blue or white scubbies are less likely to scratch the stainless.
Yes, I have heard that... green scratches, blue is safe. 
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: ynotbrusum on June 22, 2020, 07:09:28 PM
This is a good thread for newer brewers who might gain insight without having to repeat the shortcomings we have all gone through from time to time.

Craftmeister alkaline is the boss for cleaning and you can use it in repeated applications (I have a keg washer made out of a 6 gallon bucket with a submersible pump and rod with holes drilled into it to spray the inside of the keg or other vessel - I love it for my Kegmenter, too.  I tend to rinse things to remove initial deposits of crud and let them accumulate in number for series cleaning of multiple vessels in one night).  If you have some really stiff beerstone, the dairy product from the Farm & Fleet or equivalent is great as a soak (something like 3 ozs in 5 gallons soaked for a few days will literally allow wiping off the beerstone).  I had no luck with Barkeepers' Friend on beer stone - it is oxalic acid, but did not help for me in getting the oxalate off, even with a paste and significant scrubbing.  I love it however in getting the bottom of the stainless boil kettle and the SS electric elements to shine.  White or blue scrubbies or the dobie are what I use for wiping off sticky crud (never any steel wool or stainless scrubbies for the reasons stated).

I have heard that acid followed by alkaline or vice versa really clears off the beerstone quickly, so if time is a factor, those could be used in short succession, perhaps (I like to soak in the dairy product to allow the phosphoric to do its trick over a few days).

Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 22, 2020, 09:57:36 PM
I really hope I didn't damage the inside of the kegs where I used the steel wool.  I didn't need to apply much pressure as the water stains came off easily and what I used was the equivalent of an SOS pad but without the soap.  Glad I mentioned it and glad you guys brought it to my attention.  Cheers and thanks. 
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: trapae on June 22, 2020, 10:28:56 PM
Well, I soaked with the beer stone remover for two additional days and the spots vanished. I went ahead and scrubbed the bottom with barkeepers friend just to be safe and re-pacify. Hopefully that will take care of the issue. I guess just longer soaking.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 23, 2020, 12:20:16 AM
Hey, good news. 
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: HighVoltageMan! on June 23, 2020, 06:04:17 PM
There is a lot of misinformation out there about passivating stainless steel. One of being that Bar Keepers Friend will passivate stainless. Even Palmer says it can be passivated with BKF. I used to believe that until I dug deeper into the subject.

BKF contains oxalic acid, which cannot passivate stainless steel. The problem has to do with free iron molecules on the surface of the stainless which prevents chromium from oxidizing, oxalic acid cannot remove this free iron. The layer of chromium oxide is what prevents the iron in the metal from reacting to oxygen and creating iron oxide. It may be possible to create a some passivating to occur naturally after scrubbing with BKF, but it it is not consider passivation by stainless steel manufacturers. Too much free iron is on the surface to create a good layer of chromium oxide.

The only accepted way is to bath the SS in either nitric or citric acid. Citric acid is the preferred acid because not only is it way safer, but it does a better job of creating a deeper layer of chromium oxide. Both acids will remove the free iron. After a soak in the acid solution, the SS needs to be dried and exposed to air for 24-48 hours. Citric acid is available at any place that sells canning supplies for fairly cheap.

Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: MattyAHA on June 25, 2020, 02:36:52 PM
i never had a problem with oxyclean free, never needed to try another cleaner but i'm sure the alkaline craftmeister is great but its 10-12 bucks for a lb and oxy is 8 bucks for 3 lbs. i guess its a good idea to keep a lb of craftmeister around for stubborn soils but oxy has never let me down and my fermenters/kegs are squeaky clean so i see no need to spend more money on CM alkaline wash but its all about preference . as long as your gear gets cleaned who cares how you got there
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: MattyAHA on June 25, 2020, 02:43:47 PM
There is a lot of misinformation out there about passivating stainless steel. One of being that Bar Keepers Friend will passivate stainless. Even Palmer says it can be passivated with BKF. I used to believe that until I dug deeper into the subject.

BKF contains oxalic acid, which cannot passivate stainless steel. The problem has to do with free iron molecules on the surface of the stainless which prevents chromium from oxidizing, oxalic acid cannot remove this free iron. The layer of chromium oxide is what prevents the iron in the metal from reacting to oxygen and creating iron oxide. It may be possible to create a some passivating to occur naturally after scrubbing with BKF, but it it is not consider passivation by stainless steel manufacturers. Too much free iron is on the surface to create a good layer of chromium oxide.

The only accepted way is to bath the SS in either nitric or citric acid. Citric acid is the preferred acid because not only is it way safer, but it does a better job of creating a deeper layer of chromium oxide. Both acids will remove the free iron. After a soak in the acid solution, the SS needs to be dried and exposed to air for 24-48 hours. Citric acid is available at any place that sells canning supplies for fairly cheap.
idk man, palmer is a metallurgist aka a metal scientist/engineer, if he says bkf will passivate ss i'm gonna have to believe him
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: hopfenundmalz on June 25, 2020, 02:59:41 PM
Searching around the webs, I found this, which says Citric acid passivation was developed by Coors for their kegs.

https://advancedplatingtech.com/blog/nitric-vs-citric-acid-passivation/
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: denny on June 25, 2020, 03:31:53 PM
There is a lot of misinformation out there about passivating stainless steel. One of being that Bar Keepers Friend will passivate stainless. Even Palmer says it can be passivated with BKF. I used to believe that until I dug deeper into the subject.

BKF contains oxalic acid, which cannot passivate stainless steel. The problem has to do with free iron molecules on the surface of the stainless which prevents chromium from oxidizing, oxalic acid cannot remove this free iron. The layer of chromium oxide is what prevents the iron in the metal from reacting to oxygen and creating iron oxide. It may be possible to create a some passivating to occur naturally after scrubbing with BKF, but it it is not consider passivation by stainless steel manufacturers. Too much free iron is on the surface to create a good layer of chromium oxide.

The only accepted way is to bath the SS in either nitric or citric acid. Citric acid is the preferred acid because not only is it way safer, but it does a better job of creating a deeper layer of chromium oxide. Both acids will remove the free iron. After a soak in the acid solution, the SS needs to be dried and exposed to air for 24-48 hours. Citric acid is available at any place that sells canning supplies for fairly cheap.
idk man, palmer is a metallurgist aka a metal scientist/engineer, if he says bkf will passivate ss i'm gonna have to believe him

Not to mention experience.  I've used BKF to passivate SS several times and it's never failed me.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: Village Taphouse on June 25, 2020, 04:24:13 PM
I suppose there could be some variables at play as well.  If you received a very clean [used] keg and your cleaning practices were good and you also happened to have soft water, your keg may stay in very good shape.   Some of my kegs were purchased years ago when AIH was selling used ball-lock Cornelius kegs for $15.  Some looked like they had been stored at the bottom of a lake.  Yes, I cleaned them well but I also have high bicarbonate in my water and shower doors, faucets and the coffee maker all show signs of it.  I am now 50% of the way through my kegs... filled one last night with boiling water and EasyClean and left it until this morning.  A very light scrub with a green pad and it looks brand new now... sparkling clean and no buildup at all. 
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: HighVoltageMan! on June 25, 2020, 07:39:51 PM
There is a lot of misinformation out there about passivating stainless steel. One of being that Bar Keepers Friend will passivate stainless. Even Palmer says it can be passivated with BKF. I used to believe that until I dug deeper into the subject.

BKF contains oxalic acid, which cannot passivate stainless steel. The problem has to do with free iron molecules on the surface of the stainless which prevents chromium from oxidizing, oxalic acid cannot remove this free iron. The layer of chromium oxide is what prevents the iron in the metal from reacting to oxygen and creating iron oxide. It may be possible to create a some passivating to occur naturally after scrubbing with BKF, but it it is not consider passivation by stainless steel manufacturers. Too much free iron is on the surface to create a good layer of chromium oxide.

The only accepted way is to bath the SS in either nitric or citric acid. Citric acid is the preferred acid because not only is it way safer, but it does a better job of creating a deeper layer of chromium oxide. Both acids will remove the free iron. After a soak in the acid solution, the SS needs to be dried and exposed to air for 24-48 hours. Citric acid is available at any place that sells canning supplies for fairly cheap.
idk man, palmer is a metallurgist aka a metal scientist/engineer, if he says bkf will passivate ss i'm gonna have to believe him

Not to mention experience.  I've used BKF to passivate SS several times and it's never failed me.

It may passivate, but there are varying degrees of passivation. Clean SS will have limited passivation  on it's own, but nitric and citric acids will provide the best protection. It's not hard to look it up and discover this is true. If scrubbing and oxalic acid were to work, Coors wouldn't have had to spend a bunch of money looking for an alternative to nitric acid. Not only is citric acid safer, it provides better protection from corrosion.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: denny on June 25, 2020, 07:58:21 PM
There is a lot of misinformation out there about passivating stainless steel. One of being that Bar Keepers Friend will passivate stainless. Even Palmer says it can be passivated with BKF. I used to believe that until I dug deeper into the subject.

BKF contains oxalic acid, which cannot passivate stainless steel. The problem has to do with free iron molecules on the surface of the stainless which prevents chromium from oxidizing, oxalic acid cannot remove this free iron. The layer of chromium oxide is what prevents the iron in the metal from reacting to oxygen and creating iron oxide. It may be possible to create a some passivating to occur naturally after scrubbing with BKF, but it it is not consider passivation by stainless steel manufacturers. Too much free iron is on the surface to create a good layer of chromium oxide.

The only accepted way is to bath the SS in either nitric or citric acid. Citric acid is the preferred acid because not only is it way safer, but it does a better job of creating a deeper layer of chromium oxide. Both acids will remove the free iron. After a soak in the acid solution, the SS needs to be dried and exposed to air for 24-48 hours. Citric acid is available at any place that sells canning supplies for fairly cheap.
idk man, palmer is a metallurgist aka a metal scientist/engineer, if he says bkf will passivate ss i'm gonna have to believe him

Not to mention experience.  I've used BKF to passivate SS several times and it's never failed me.

It may passivate, but there are varying degrees of passivation. Clean SS will have limited passivation  on it's own, but nitric and citric acids will provide the best protection. It's not hard to look it up and discover this is true. If scrubbing and oxalic acid were to work, Coors wouldn't have had to spend a bunch of money looking for an alternative to nitric acid. Not only is citric acid safer, it provides better protection from corrosion.

I have no doubt that's true, but for my purposes BKF worked great.  Took the rust off a poorly cut keg and it has not returned after 8 years.
Title: Re: Dark spots, ? beer stones in the bottom of my keg...What to do?
Post by: erockrph on June 25, 2020, 08:37:06 PM
There is a lot of misinformation out there about passivating stainless steel. One of being that Bar Keepers Friend will passivate stainless. Even Palmer says it can be passivated with BKF. I used to believe that until I dug deeper into the subject.

BKF contains oxalic acid, which cannot passivate stainless steel. The problem has to do with free iron molecules on the surface of the stainless which prevents chromium from oxidizing, oxalic acid cannot remove this free iron. The layer of chromium oxide is what prevents the iron in the metal from reacting to oxygen and creating iron oxide. It may be possible to create a some passivating to occur naturally after scrubbing with BKF, but it it is not consider passivation by stainless steel manufacturers. Too much free iron is on the surface to create a good layer of chromium oxide.

The only accepted way is to bath the SS in either nitric or citric acid. Citric acid is the preferred acid because not only is it way safer, but it does a better job of creating a deeper layer of chromium oxide. Both acids will remove the free iron. After a soak in the acid solution, the SS needs to be dried and exposed to air for 24-48 hours. Citric acid is available at any place that sells canning supplies for fairly cheap.
idk man, palmer is a metallurgist aka a metal scientist/engineer, if he says bkf will passivate ss i'm gonna have to believe him

Not to mention experience.  I've used BKF to passivate SS several times and it's never failed me.

It may passivate, but there are varying degrees of passivation. Clean SS will have limited passivation  on it's own, but nitric and citric acids will provide the best protection. It's not hard to look it up and discover this is true. If scrubbing and oxalic acid were to work, Coors wouldn't have had to spend a bunch of money looking for an alternative to nitric acid. Not only is citric acid safer, it provides better protection from corrosion.
No doubt Coors has a lot more invested in their brewhouse and it sees a lot more use than the typical homebrewer. While oxalic acid passivation may not be up to ASM standards, it is certainly good enough for most homebrewers.

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