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Author Topic: Brewing pot gave water a metallic taste  (Read 2338 times)

Offline joe_meadmaker

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Brewing pot gave water a metallic taste
« on: February 12, 2021, 07:56:06 pm »
In the Other Fermentables category I recently posted a topic that I'm planning to make a snow mead.  I got a good snowfall at my house, and so I melted a bunch in a pot with the intent to make a mead with it tomorrow.  The snow was gathered and melted on Tuesday.  Tonight I tasted the water to make sure it seemed okay, but it had a metallic taste.  I dumped the metallic water, and have a couple other small pots and plenty of snow left in the yard for tomorrow.  But now I'm concerned about my big boiling pot.

It's a 20 gallon pot.  The brand on the bottom is Thunder Group.  Does anyone think I should be concerned about using this pot for brewing?  I've been using it for 8 years or so at this point.  I haven't had any issues (that I'm aware of) with the beer made in it.  Part of me thinks the pot just isn't designed to store water for several days.  I was thinking I would give it a good soak with PBW, but wanted to see if anyone had other thoughts.  Should I abandon this pot and get a new one?

Offline Oiscout

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Re: Brewing pot gave water a metallic taste
« Reply #1 on: February 12, 2021, 08:06:32 pm »
In the Other Fermentables category I recently posted a topic that I'm planning to make a snow mead.  I got a good snowfall at my house, and so I melted a bunch in a pot with the intent to make a mead with it tomorrow.  The snow was gathered and melted on Tuesday.  Tonight I tasted the water to make sure it seemed okay, but it had a metallic taste.  I dumped the metallic water, and have a couple other small pots and plenty of snow left in the yard for tomorrow.  But now I'm concerned about my big boiling pot.

It's a 20 gallon pot.  The brand on the bottom is Thunder Group.  Does anyone think I should be concerned about using this pot for brewing?  I've been using it for 8 years or so at this point.  I haven't had any issues (that I'm aware of) with the beer made in it.  Part of me thinks the pot just isn't designed to store water for several days.  I was thinking I would give it a good soak with PBW, but wanted to see if anyone had other thoughts.  Should I abandon this pot and get a new one?
Could be some type of polluted precipitation z not to get political but we don't currently live in the most healthy of times as far as terrestrial cleanliness goes

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Offline mabrungard

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Re: Brewing pot gave water a metallic taste
« Reply #2 on: February 12, 2021, 08:43:33 pm »
Water like rainwater, has very low dissolved content. That condition can be very corrosive and it’s possible that some of the kettle ended up in that water.
Martin B
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Offline joe_meadmaker

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Re: Brewing pot gave water a metallic taste
« Reply #3 on: February 12, 2021, 09:07:21 pm »
Could be some type of polluted precipitation z not to get political but we don't currently live in the most healthy of times as far as terrestrial cleanliness goes

That's not a bad thought, but I don't think that was the problem.  While I was gathering snow, I put some in a glass and melted it.  It actually tasted quite clean and good.


Thanks for the input Martin.  I'll give it a good cleanup and keep going with it.

Offline BrewBama

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Brewing pot gave water a metallic taste
« Reply #4 on: February 12, 2021, 09:10:50 pm »
Water like rainwater, has very low dissolved content. That condition can be very corrosive and it’s possible that some of the kettle ended up in that water.
Martin, am I correct in saying that because the snow melt had little dissolved content, it had less buffering power (resistance to pH change), therefore the moment it comes in contact with air, CO2 gas begins dissolving into it, forming carbonic acid and lowering the pH (corrosiveness)?


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« Last Edit: February 12, 2021, 09:14:16 pm by BrewBama »

Offline majorvices

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Re: Brewing pot gave water a metallic taste
« Reply #5 on: February 13, 2021, 02:06:35 pm »
If you are concerned about the kettle and assuming it is stainless steel PBW won't do anything. The kettle might need passivated with an acid. You could try citric acid. I'm not sure what concentration though. In the brewing industry it is common to use phosphoric acid at double cleaning strength and let sit over night without rinsing to air out and passivate. Passivation "reseals" the stainless with an oxidative layer and removes metallic particles.

Star San sells Acid #5 which is phosphoric acid but not sure how much it costs.

Offline mabrungard

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Re: Brewing pot gave water a metallic taste
« Reply #6 on: February 13, 2021, 04:16:05 pm »
Martin, am I correct in saying that because the snow melt had little dissolved content, it had less buffering power (resistance to pH change), therefore the moment it comes in contact with air, CO2 gas begins dissolving into it, forming carbonic acid and lowering the pH (corrosiveness)?

Somewhat, but the low TDS also invites metal ions to dissolve.
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Offline Bilsch

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Re: Brewing pot gave water a metallic taste
« Reply #7 on: February 13, 2021, 05:05:26 pm »
If you are concerned about the kettle and assuming it is stainless steel PBW won't do anything. The kettle might need passivated with an acid. You could try citric acid. I'm not sure what concentration though. In the brewing industry it is common to use phosphoric acid at double cleaning strength and let sit over night without rinsing to air out and passivate. Passivation "reseals" the stainless with an oxidative layer and removes metallic particles.

Star San sells Acid #5 which is phosphoric acid but not sure how much it costs.

Citric acid at 4% solution @160f for an hour or two is the best method. Citric is cheap, easy to handle and environmentally benign. While doing your kettle be sure to toss all your other stainless equipment, you can fit, in there and do it all at the same time. Fun fact.. Coors actually discovered the critic method and used in their brewery. Their white paper is a great read: "Stainless Steel flavor contribution to beer" and can be found here:
http://www.enviro-britesolutions.com/wp-content/uploads/2019/04/Coors-Paper.pdf

Five star acid #5 does contain phosphoric acid but also nitric acid and it is the HNO3 that does the passivating. To be more specific what nitric and citric do is remove iron at the surface of the stainless thus enriching the chromium layer. There is bad advice still roaming the forums that phosphoric can remove the surface iron but this is not the case. Passivation actually happens later when the newly exposed chromium layer oxidizes in air. Nitric can also oxidize the Cr while removing the Fe but usually only in higher concentrations then is contained in FSA#5.
« Last Edit: February 13, 2021, 05:19:38 pm by Bilsch »

Offline joe_meadmaker

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Re: Brewing pot gave water a metallic taste
« Reply #8 on: February 13, 2021, 06:53:32 pm »
Thanks for the info on passivating!  I'll give that a try.

Fire Rooster

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Re: Brewing pot gave water a metallic taste
« Reply #9 on: February 14, 2021, 01:42:57 am »
This thread just reminded me that 2 SS pots are due to be cleaned/passivated with Bar Keepers Friend.

Thanks

Topic for another day, there are different grades of SS.
It was another reason the hop spider was ditched, it was clearly rusting.
A nonreactive polished thick SS 18/10 slotted spoon is used to stir the mash.
https://www.williams-sonoma.com/products/williams-sonoma-deep-slotted-spoon/?pkey=s%7Cslotted%20spoon%7C77

If you ever tasted the soup spoon while having highly acidic tomato soup,
it was a sign of lower grade SS, and didn't react well to the acids.

Better grades of SS are costly, but as BrewBama mentioned, buy once cry once.
I have enough going on with brewing, don't need metallic taste being added to it.

« Last Edit: February 15, 2021, 07:44:57 am by Fire Rooster »

Offline majorvices

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Re: Brewing pot gave water a metallic taste
« Reply #10 on: February 14, 2021, 06:19:43 am »
If you are concerned about the kettle and assuming it is stainless steel PBW won't do anything. The kettle might need passivated with an acid. You could try citric acid. I'm not sure what concentration though. In the brewing industry it is common to use phosphoric acid at double cleaning strength and let sit over night without rinsing to air out and passivate. Passivation "reseals" the stainless with an oxidative layer and removes metallic particles.

Star San sells Acid #5 which is phosphoric acid but not sure how much it costs.

Citric acid at 4% solution @160f for an hour or two is the best method. Citric is cheap, easy to handle and environmentally benign. While doing your kettle be sure to toss all your other stainless equipment, you can fit, in there and do it all at the same time. Fun fact.. Coors actually discovered the critic method and used in their brewery. Their white paper is a great read: "Stainless Steel flavor contribution to beer" and can be found here:
http://www.enviro-britesolutions.com/wp-content/uploads/2019/04/Coors-Paper.pdf

Five star acid #5 does contain phosphoric acid but also nitric acid and it is the HNO3 that does the passivating. To be more specific what nitric and citric do is remove iron at the surface of the stainless thus enriching the chromium layer. There is bad advice still roaming the forums that phosphoric can remove the surface iron but this is not the case. Passivation actually happens later when the newly exposed chromium layer oxidizes in air. Nitric can also oxidize the Cr while removing the Fe but usually only in higher concentrations then is contained in FSA#5.

Thanks for the clarification -- nitric (or citric) acid not phosphoric acid for passivation.

I went back and rechecked this this morning and found an article from Palmer in How to Brew that says that passivation on small items can be used with an oxalic acid based kitchen cleanser and a green or white scrubby. I remembered reading that years ago.


http://howtobrew.com/book/appendices/appendix-b/passivating-stainless-steel
« Last Edit: February 14, 2021, 06:25:35 am by majorvices »

Fire Rooster

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Re: Brewing pot gave water a metallic taste
« Reply #11 on: February 14, 2021, 06:30:46 am »
 

I went back and rechecked this morning and found an article from Palmer in How to Brew that says that passivation on small items can be used with an oxalic acid based kitchen cleanser and a green or white scrubby. I remembered reading that years ago.

http://howtobrew.com/book/appendices/appendix-b/passivating-stainless-steel

[/quote]

Cleaned/passivated 2 SS pots this morning. Used a green/white scrubby sponge and "Soft Cleanser" Bar Keepers Friend, which has oxalic acid & citric acid in it.
I've seen "Soft Cleanser" Bar Keepers Friend in the supermarket, Lowes, Home Depot.

Just dawned on me, is the OP's pot SS or aluminum ?
http://www.thundergroup.com/app/stx.productdetail.asp?did=951
« Last Edit: February 14, 2021, 04:56:53 pm by Fire Rooster »

Offline Bilsch

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Re: Brewing pot gave water a metallic taste
« Reply #12 on: February 14, 2021, 06:48:55 pm »
Here is a good article on passivation I think every brewer should read to put to bed some of the bad information still circulating.

"A common misconception among home brewers is that passivation can be done with any acid. Many brewers have an oxalic acid, phosphoric acid, and/or any abrasive based cleaner handy and think that it can be also used to passivate their stainless steel. These cleaners can help remove residue, remove rust, or bring the stainless steel surface down to bare metal, but they do not selectively remove iron. The stainless steel surface will form the oxide layer (as it normally does), but without a correct acid treatment the chromium only covers about 18% of the surface. In other words, there's no passivation benefit from these acids."

https://brewingforward.com/wiki/Passivation

Fire Rooster

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Re: Brewing pot gave water a metallic taste
« Reply #13 on: February 15, 2021, 01:49:15 am »
Here is a good article on passivation I think every brewer should read to put to bed some of the bad information still circulating.

"A common misconception among home brewers is that passivation can be done with any acid. Many brewers have an oxalic acid, phosphoric acid, and/or any abrasive based cleaner handy and think that it can be also used to passivate their stainless steel. These cleaners can help remove residue, remove rust, or bring the stainless steel surface down to bare metal, but they do not selectively remove iron. The stainless steel surface will form the oxide layer (as it normally does), but without a correct acid treatment the chromium only covers about 18% of the surface. In other words, there's no passivation benefit from these acids."

https://brewingforward.com/wiki/Passivation

Very good information, thank you.

Bar Keepers Friend isn't one product, there are many. https://www.barkeepersfriend.com/
I went to Bar Keepers Friend website to check ingredients in their products.
There are two products, based on label, a home brewer would probably
select.  The "powdered cleanser" and "soft cleanser" versions, both have oxalic acid.
But only the "soft cleanser" version includes citric acid, and has more citric acid than oxalic acid.

After I use the "soft cleanser" version on SS pots, the pots will have a very slight blue sheen.
I'm solely focused on the home brewer scale.  It's obviously impractical for commercial
brewers to use a scrubby on many large tanks.

If my Father was still around I would pick his brain, he was a Metallurgist.

Innocent oversight on the authors part under Myth Busting.  Bar Keepers Friend is a brand name, not a specific product.
Their "powdered cleanser" product was commonly used, as was Comet.  Since the
"soft cleanser" version includes citric acid, and not solely oxalic acid, it nullifies
the belief "Bar Keepers Friend" won't work.
« Last Edit: February 15, 2021, 10:38:53 am by Fire Rooster »

Offline ynotbrusum

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Re: Brewing pot gave water a metallic taste
« Reply #14 on: February 15, 2021, 11:13:28 am »
Yes, good information.  I have used a dairy industry product "Milk Stone Remover" at a fairly dilute  level - 3 ounces in 5 gallons, to remove beer stone build up from time to time.  A prolonged soak of a few days usually allows it to be wiped off and cleaned and then air dried to re-passivate.  It contains phosphoric acid:

https://www.farmandfleet.com/products/979692-stearns-dairyland-brand-sterosol-milkstone-remover-and-acid-rinse.html

A little lasts a long time based on my experience.  I put each of my 17 kegs through a thorough beer stone removal and cleaning and re-passivating and then multiple rinses and final sanitizing and purging over the last year or so, as they are rotated through filling and dispense.

But for most new manufactured products the mfg suggests a good cleaning initially with a percarbonate or similar cleaner, then thorough rinsing before use.
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