# Potassium Metabisulfite Aging



## Sudz (Apr 7, 2012)

I've been struggling with verification of my A/O SO2 system using standard solutions of potassium metabisulfite mixed to provide a 50 ppm test mixture. 

I'm beginning to think the K-meta I'm using may be weak. Test results on wine appear reasonable but all of my attempts to use a SO2 test solution come back very weak.

Does potassium metabisulfite have a limited shelf life? Could old stock account for x3 factor lower solution strength than expected?

Thanks...


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## Runningwolf (Apr 7, 2012)

Sudz, meta does break down after a year but not like Sorbate. Keep your chemicals in a cool dark place. I honestly find that if I nned to add a certain amount of meta to acheave a target, you really almost need to add 25-30% more to get there. I think this is the trouble you're having if you testing at again a week later or so after adding. When you add meta a certain amount will be free (which you're testing for) and the rest will be bound. Becareful though with what I said. Once you hit your target ppm in the future just add the amount you calculated for. You are using the A/O system which is the most accurate test you can use so if all your testing chemicals are fresh, what you're saying about the meta could be true. Remember even at bottling time if you are filtering and bottling at the same time you will be loosing a fair amount in that process.


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## Sudz (Apr 9, 2012)

I picked up a new bottle of potassium metabisulfite and mixed a fresh dose of 50ppm SO2. Ran three samples through my A/O system with a spread of 48.1 ppm through 49.3 ppm.

Problem solved! My old Kmeta was running about 20% of full strength. In all fairness it was several years old.

This also explains why my wines are crashing at about 6 months in. I'm measuring SO2 on these in the 12 - 15 ppm range which is a result of using weak Kmeta blindly.

Live and learn I guess. 

Now if I can just salvage my Cellar Classic Amarone which has been sitting in the secondary for about a month with only 14 ppm SO2. I'll bump it to about 36 ppm, watch it a few days and if stable, bottle it and cross my fingers.

This forum was a great source of assistance in getting this sorted out. Thanks to all who pitched in.


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## robie (Apr 9, 2012)

Also to consider, each time you add SO2, a portion of it gets immediately bound up, leaving you with less free SO2 than you might have expected. Each time you add more SO2, this percentage that is immediately bound up lessen.


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## Runningwolf (Apr 9, 2012)

Don't dump the old meta. Use it for sanitising.


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## Sudz (Apr 10, 2012)

Other than solving my problem I reaffirmed an important lesson. 

If you can't measure it, you're leaving everything to luck. And I've yet to find a good way to manage luck.... 

I can measure pH, TA, and SO2 now with some degree of certainty. This should help me in improving my wines hopefully.


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## robie (Apr 10, 2012)

Sudz said:


> Other than solving my problem I reaffirmed an important lesson.
> 
> If you can't measure it, you're leaving everything to luck. And I've yet to find a good way to manage luck....
> 
> I can measure pH, TA, and SO2 now with some degree of certainty. This should help me in improving my wines hopefully.



That's called gaining in wisdom and experience. Makes you a better wine maker, which is what all of us want to become.


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## robie (Mar 25, 2013)

I know this is an old thread but I want to let everyone know.

Tonight I opened a brand new heat-sealed milar, one-pound bag of Kmeta. It was vacuum sealed, so there were no leaks.

I noticed that it didn't have any clumps like a punch pf Kmeta generally does. It had the consistency of sugar.

For a Kmeta solution, I mixed 3 tablespoons of it in a gallon of water, like I have done may times before.

I shock it up really well and opened the lid and took a careful whif. Nothing! I might just as well have mixed in 3 tablespoons of sugar or salt!!!

Granted, it was stored in that vacuum sealed bag in a closed box for a little over a year, but in a heavy milar bag, one would think it would last for several years.

I got on the internet and looked up shelf-life of Potassium Meta bi-sulfate in powder form and everything said it should last for years in such a well sealed container.

Just think might have happened if I had use it for something critical.

As a caution, always take a careful whif of your solution to make sure it is fresh and powerful. If you can stand the smell without jerking back, it is very likely not any good.


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## dralarms (Mar 26, 2013)

So, what you are saying is that if my 3 tbps per gallon of k-meta should "take my breath away"? This stuff takes my breath away dry.


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## Arne (Mar 26, 2013)

robie said:


> I know this is an old thread but I want to let everyone know.
> 
> Tonight I opened a brand new heat-sealed milar, one-pound bag of Kmeta. It was vacuum sealed, so there were no leaks.
> 
> ...


 
Robie, give it a couple of days, then try another little sniff. I had some I mixed with no oder, let it alone and a few days later it was really strong. I have no reason for it, it just worked out that way. Arne.


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## Sudz (Mar 26, 2013)

Arne said:


> Robie, give it a couple of days, then try another little sniff. I had some I mixed with no oder, let it alone and a few days later it was really strong. I have no reason for it, it just worked out that way. Arne.


 
I've experienced the same thing. Let it sit and give it a whiff.

However, before developing a good method for measuring SO2 I had been having my reds crash after several months in the bottle. I discovered that the kmeta I had been using was only about 20% full strength. 
Admittedly I had the stuff for over a year but it had been in a good environment in it's original plastic bottle. Today I just buy fresh stock about every six months and use the existing as sanitizer.


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## WI_Wino (Mar 26, 2013)

Pardon the newb question but when you say your wine crashes at 6 months, does it mean tastes terrible like vinegar or something? Or does it start to taste not as good as it used to?


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## Sudz (Mar 26, 2013)

Sorry. 

What I meant was generally things progress in a favorable direction as the wine ages and then abruptly changes direction and begins to taste badly. At that point, the longer it goes the worse it gets. My term is the stuff crashed... There's probably an official term but I don't know it.


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## robie (Mar 26, 2013)

Arne said:


> Robie, give it a couple of days, then try another little sniff. I had some I mixed with no oder, let it alone and a few days later it was really strong. I have no reason for it, it just worked out that way. Arne.



I checked it out again this morning and it was like sniffing water. I really wonder if the stuff is really KMETA and not some mix up at the supplier.


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## dralarms (Mar 26, 2013)

Robbie,

I've got some made about a month ago. I used some last night and about killed me. I've been storing my carboys with k-meta in them and after cleaning out one I poured some in and the odor was very strong.


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## robie (Mar 26, 2013)

dralarms said:


> Robbie,
> 
> I've got some made about a month ago. I used some last night and about killed me. I've been storing my carboys with k-meta in them and after cleaning out one I poured some in and the odor was very strong.



Yep, that's the way it is supposed to be. 

I always store a cup or two of the solution sealed up in each empty carboy.

This issue really bothers me because a newbie wouldn't necessarily know if the Kmeta powder is bad. had I first started oyt with this same batch, I wouldn't have suspected anything until maybe later I read something about a Kmeta solution needing to "knocking you back". This could easily result in a ruined batch or 2 of wine.


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## dralarms (Mar 26, 2013)

Yep,

I bought a 50 lb bag of it from a chemical plant. Seems to be fresher than the stuff you get in the lbs


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## Chiumanfu (Mar 26, 2013)

50lbs! Exactly how much wine are you making?


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## dralarms (Mar 26, 2013)

Lol. I got it at a deal. But I'm making all I can and still stay legal.


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## Chiumanfu (Mar 27, 2013)

Will kmeta powder last longer if its stored in a air tight container in the freezer?


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## Runningwolf (Mar 27, 2013)

Robbie add some citric acid to it. I always blend the two together for a better sanitizing solution. Thats really a standard practice.


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## Runningwolf (Mar 27, 2013)

Chiumanfu said:


> Will kmeta powder last longer if its stored in a air tight container in the freezer?


 Keep in air tight container in dark and it should be good for at least 18 months. After that use it only for sanitizing. But only what you'll need for next 6 months or so.


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