Ongoing sulfide issues...

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Bliorg

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Hi all -

I have a batch of berry/dragon fruit going right now. Fermentation was uneventful. If anything, it was perfect for this - used K1-V1116, the ferment was cool, two additions of Fermaid-O. Fermented to dryness with lots of nice, fruity aromas. Sulfited when racked. Dropped a lot of solids, but wasn't able to rack off the lees for about a week. Developed a very strong sulfide odor, though taste was good. Have been battling this now for a month. Have racked with sulfite, degassed several times with a whip, dosed with Reduless and fined with Super Kleer. Thought I was on the good side of it, couldn't smell any more sulfide after the last racking and flavor was still very nice. Started working on a haze that's in the wine. Added pectic enzyme and put a FermWrap on it (it's in the ~48 degree garage). After 4 days, the sulfide odor is back.

I'm kind of at a loss as to what to do next. I'm not sure if Reduless can be tried again. I'm hesitant to dose it with sulfite again, as I feel I'm walking a tightrope on over-sulfiting it. Our buddy Ed (or whoever writes the EC Kraus blog, I can't really imagine it is Ed) fully endorses racking through copper:
1614440476786.png
I've dropped plenty of pennies into nitric acid, so I know what low pH does to copper, and while I'm sure this works, I agree with the consensus that it's likely all bad. I'd need to understand the chemistry much more to risk that. I don't want to beat it up with the whip again, and even so, the last time didn't evolve any gas at all. I'd like to get this into bottle sometime soon-ish, so it's ready for spring. I'm at a loss, as the H2S seems to be transient.

Thoughts? Help me, Obi-wan!
 

sour_grapes

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I will say that almost everything that Ed Kraus wrote in that reply was incorrect.

It is true that the only copper sulfate that forms is due to the sulfur present (Duh :slp ). However, it does not dissipate as a gas. Moreover, copper will be dissolved without forming copper sulfate, i.e., loose copper ions.
 

Bliorg

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I will say that almost everything that Ed Kraus wrote in that reply was incorrect.

It is true that the only copper sulfate that forms is due to the sulfur present (Duh :slp ). However, it does not dissipate as a gas. Moreover, copper will be dissolved without forming copper sulfate, i.e., loose copper ions.
I know, right? Almost comical if it weren't actually a bit scary.

FWIW, the sulfide smell is mostly gone today. I'm not sure why it keeps coming and going. I think it's going to get another light-ish dose of sulfite and will just sit a while after that. Hopefully time helps a bit.
 

winemaker81

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In the distant past, we racked over clean copper pennies to address H2S. It worked.

However, it produces copper sulfate, which is highly poisonous.

The problem with racking over copper is that you have NO idea how much copper sulfate you're introducing into your wine. As recently as last fall I was of the opinion that racking over copper, as a last resort, is ok.

Since then I've performed more research on the topic and my opinion has changed to, "just say no".

I personally encountered H2S for the first time last fall. I splash racked, stirred the heck out of the wine, and hit it with a triple dose of K-meta. After that the wine had a slight smell and off-taste, so I used Reduless. I racked yesterday and it's got an off-taste and smell.

Some effects of H2S are not correctable. I'm hoping I'm not in that situation.

I read one source that said Reduless can be used more than once. I'm considering that, but have not yet made that determination.
 

DizzyIzzy

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Hi all -

I have a batch of berry/dragon fruit going right now. Fermentation was uneventful. If anything, it was perfect for this - used K1-V1116, the ferment was cool, two additions of Fermaid-O. Fermented to dryness with lots of nice, fruity aromas. Sulfited when racked. Dropped a lot of solids, but wasn't able to rack off the lees for about a week. Developed a very strong sulfide odor, though taste was good. Have been battling this now for a month. Have racked with sulfite, degassed several times with a whip, dosed with Reduless and fined with Super Kleer. Thought I was on the good side of it, couldn't smell any more sulfide after the last racking and flavor was still very nice. Started working on a haze that's in the wine. Added pectic enzyme and put a FermWrap on it (it's in the ~48 degree garage). After 4 days, the sulfide odor is back.

I'm kind of at a loss as to what to do next. I'm not sure if Reduless can be tried again. I'm hesitant to dose it with sulfite again, as I feel I'm walking a tightrope on over-sulfiting it. Our buddy Ed (or whoever writes the EC Kraus blog, I can't really imagine it is Ed) fully endorses racking through copper:
View attachment 72117
I've dropped plenty of pennies into nitric acid, so I know what low pH does to copper, and while I'm sure this works, I agree with the consensus that it's likely all bad. I'd need to understand the chemistry much more to risk that. I don't want to beat it up with the whip again, and even so, the last time didn't evolve any gas at all. I'd like to get this into bottle sometime soon-ish, so it's ready for spring. I'm at a loss, as the H2S seems to be transient.

Thoughts? Help me, Obi-wan!
Have you considered purchasing a copper WHISK (which is used in cooking)?.....................................DizzyIzzy
 

cmason1957

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Have you considered purchasing a copper WHISK (which is used in cooking)?.....................................DizzyIzzy
Using a copper whisk for cooking is much different than putting it into an acid solution like wine. It might be great for a test, where you throw away the test and don't drink it. Copper poisoning is a real thing.
 

DizzyIzzy

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Using a copper whisk for cooking is much different than putting it into an acid solution like wine. It might be great for a test, where you throw away the test and don't drink it. Copper poisoning is a real thing.
Disagree...................copper whisks graded for cooking can be used in many solutions, including wine.................................DizzyIzzy
 

winemaker81

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Disagree...................copper whisks graded for cooking can be used in many solutions, including wine
Research copper sulfide sulfate. It's a deadly poison in low concentrations. Don't mess with it.

EDIT: I used the wrong term -- copper sulfate is the poison.
 
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Bliorg

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Okay, because these things interest me, I did some research into the two copper sulfides (copper (I) sulfide, Cu2S, and copper (II) sulfide, CuS):
  • Neither seem to have set exposure limits for ingestion.
  • Sulfur salts of heavy metals (of which copper is one) are generally very slightly soluble, or completely insoluble, in aqueous solution. To wit: Copper (II) sulfide solubility is given as 0.000033 g/100 ml @ 18C (per the below referenced SDS); copper (I) sulfide is given as completely insoluble in water.
  • Density of copper (II) sulfide is given as 4.6 g/cm3; copper (I) sulfide as 5.6 g/cm3.
  • As wine is not a neat aqueous solution, I checked my Lange's: copper (I) sulfide and copper (II) sulfide are both given as insoluble in aqueous solution, but soluble in solutions of HNO3.
  • Both salts are incompatible with strong oxidizers (including HNO3), and on decomposition produce H2S, which is a toxic gas.
Okay, so here’s how I think this information can be applied: The reaction I believe is favored is 2Cu + H2S -> Cu2S + H2, though I need to look up activation energies and see. Regardless, the copper combines with the sulfur and produces Cu2S, which, as a sulfur salt of a heavy metal, is insoluble, is significantly more dense than wine, and precipitates out of solution. The low pH isn’t enough to dissociate the copper (not a strong acid), so there should be no free copper ions in solution in the wine. So, the reaction takes place, the salt drops out, and with proper clearing, fining, and filtration, none of the salt should remain in the wine. If the salt were ingested, the toxicity comes from the decomposition of the salt to H2S by the HCl in the stomach.

Now, let’s say that the other reaction, Cu + H2S -> CuS + H2, is the dominant one. Same thing happens: The salt is very, very, very slightly soluble in aqueous solution (so slightly that I think it can be considered insoluble for this purpose, which is borne out by Lange’s) and again due to the higher density, would precipitate out when formed. Proper technique would then remove it from the wine.

Whether or not anyone chose to use the Brillo pad technique our buddy Ed endorses is up to them. It is (as most wine making decisions are) a risk-based decision (or should be). I tend to be incredibly risk averse, but I think, with more research, I might not be so afraid of this one. That decision is an individual thing – the best thing to do is run some testing with some wine and some copper, send samples out for testing, and have a definitive answer. Barring that, well, you weigh risk and benefit against severity and likelihood.

This is obviously not exhaustive, but rather, I hope, a start of a discussion.

References:
Copper Sulfide CuS
Copper Sulfide Cu2S
https://www.onboces.org/cms/lib/NY02216875/Centricity/Shared/MSDS C_List/Copper Sulfide.pdf
Lange’s Handbook of Chemistry, 14th ed., pg 3.29
 

winemaker81

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@Bliorgl, thanks for doing the research on this. I like seeing technical answers to questions like this.

I checked a couple of links and realize I used the wrong term -- copper sulfate is the deadly poison, not sulfide.

Me? Hopefully I have learned enough that I'll never experience H2S again, but if I do, I'll again use a commercial reducing product as I can control the dosage. I'm willing to take a lot of risks, but I view copper sulfide in the same light as fugu * and jumping out of airplanes that are not crashing. Others can do it, but I'll pass.


* Fugu is the poisonous puffer fish that is a highly dangerous delicacy in Japan.
 

NorCal

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There was a very popular wine supply site that promoted the uncontrolled use of copper to resolve H2S. Regardless of the info I sent them, they would not remove this recommendation from their site. I contacted the health dept. in their state and had a discussion with them. They were shocked that the wine supply company was recommending the use of uncontrolled copper in wine and the agency that controls their permit strongly suggested they remove it. It was gone the next day.
 

sour_grapes

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Very interesting. I am sure to learn a lot. However, I have a question:

The low pH isn’t enough to dissociate the copper (not a strong acid), so there should be no free copper ions in solution in the wine.
This is the assumption I am questioning. I have been basing (no pun intended) my opposition to unregulated copper treatments on the assumption that there can be free copper ions created at low pH. For example, consider the following paper:

A practical guide for determining the solubility of metal hydroxides and oxides in water," Dyer, James A.; Scrivner, Noel C.; Dentel, Steven K. E.I. DuPont de Nemours and Co., Wilmington, DE, USA. Environmental Progress (1998), 17(1), 1-8.

I find graphs like this one from that paper convincing:




Note that the y-axis is logarithmic, and that the lowest pH on that graph is about 5.5. Wine is about 100x more acidic at pH of ~3.6.

No specifications were made in the paper other than the value of the pH. Is that incorrect? I.e., do you need to specify the acid as well?
 
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stickman

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Copper will release some ions at low pH and it doesn't take much to cause problems with wine. For our discussion it doesn't really matter what drives the pH down, though the other ions present will determine to some extent what reactants are produced. There's some good information in the article below.

 

Cap Puncher

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I used Redulees twice on a pinotage batch gone wrong.
I agree, I have used Reduless more than once, even a 3rd time on some batches. Do bench trials if you can. It's can work. Also, I have used copper on batches previous with with only to find that the sulfur smell re-emerged months later. I was using argon to purge the headspace. I later learned that I probably kept the red wine in too reductive of a state and the reaction might have reversed, re-releasing the sulfide. See article for more explanation. So it better to be more oxidative (obviously not over doing it) when you have used copper.

I checked a couple of links and realize I used the wrong term -- copper sulfate is the deadly poison, not sulfide.
As for copper sulfate, it is poisonous at certain concentration just like anything. Acetaminophen (Tylenol)is poisonous at high doses. Methanol is poisonous and is in most batches of wine (probably all wine) at certain concentrations. Copper is allowable in drinking water at 1.3mg/L (1.3 ppm) per the EPA. The upper limit of daily allowance of copper in adults is about 10mg. Copper is necessary as a cofactor to many enzymatic reactions in your body. I dose copper in TPNs for patients all the time.

Sulfates are allowable in drinking water up to 250mg/L.

What I'm trying to say is Copper sulfate can be used in wine without ill effects if using the proper dosage.

Though I have gravitated to using Reduless in most instances (more so because it pulls the Cu Sulfide complex out of solution since it attaches to the inactivated yeast) but I am not afraid to use copper sulfate if I need it. Now, both products will strip aroma and character from the wine. Also, too much copper sulfate (even at safe doses) might impart an unpleasant bitterness in your wine. Again, bench trials (and my wife's nose).

This year, I am a Renaissance Yeast convert and hopefully won't be dealing with sulfide issues at all!
 

winemaker81

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As for copper sulfate, it is poisonous at certain concentration just like anything. Acetaminophen (Tylenol)is poisonous at high doses. Methanol is poisonous and is in most batches of wine (probably all wine) at certain concentrations. Copper is allowable in drinking water at 1.3mg/L (1.3 ppm) per the EPA. The upper limit of daily allowance of copper in adults is about 10mg. Copper is necessary as a cofactor to many enzymatic reactions in your body. I dose copper in TPNs for patients all the time.
I agree. When I use Reduless, I am using copper to treat the wine. The difference between that and racking over copper is that I am strictly controlling the amount of copper being added to my wine.

My point is to ensure that others are aware of that danger, so they can make an informed decision.
 

KCCam

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I agree. When I use Reduless, I am using copper to treat the wine. The difference between that and racking over copper is that I am strictly controlling the amount of copper being added to my wine.

My point is to ensure that others are aware of that danger, so they can make an informed decision.
I'm with you. And it's exactly discussions like this that help to inform people. Not everyone realizes copper can produce toxic chemicals and is toxic at a certain concentration. If someone offered me a bottle of wine and said, "I put some methanol in this. I'm not sure how much I added, or how much it would take to kill you, but I read on the internet that lots of people add some, and it doesn't seem to bother them," I'd say "No thanks."

@Cap Puncher says the daily limit of copper in drinking water is 10 ppm. @sour_grapes' chart suggests that any pH below about 6.5 would allow greater than 10 ppm of copper in solution. The trend obviously must level off, because a linear extrapolation would suggest 10 million ppm at pH 3.5, or 10 grams copper per gram of solvent. But at pH 5.5, the solubility is already 100 times the limit. So how much copper actually does dissolve from the copper tube you rack with, or the pennies you rack over (for non-Canadians, lol), or the copper pad you rack through? Who knows? If you have a very accurate scale, maybe you could weigh it. 0.03 g of coper in 23 L of wine would be 1.3 ppm. It wouldn't take many solids from the wine, or wine itself, left on the copper after the racking to widely skew those results. But what we do know, is that if you prescribe copper to a patient, or use a product like Reduless, then you are guaranteed a certain dose.

Plus.... The references for some of the statements above (including mine) and some of the charts you might see elsewhere, may not be cited*, so we are assuming the people that make them know what they're talking about, and that they are accurate. I believe they do, and they are, but I also now believe I need to be careful with copper, and I will not be adding unknown quantities of it to my wine, for any reason.

*Edited to correct my oversight that @sour_grapes actually did cite his reference. Duh. :e
 
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KCCam

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and I DID cite the source. :wy
OOOOOPS! "Damn it Jim," as Bones would say, I missed that "that," and didn't make the connection. I should have known better. So glad I didn't offend you. Thanks for the correction, I appreciate you keeping me honest, and I've edited my post. I actually almost didn't post that reply, and I pray I haven't offended anyone else.
 
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