SO2

K-meta is about 58% SO2.

Campden tablets are designed to have about 0.44 grams of (often K-) meta. Whether they are 48% SO2 or not really depends on the tablet size, which tends to vary depending on the manufacturing process.

It means you'll get ~58% *total* SO2. Some of that will then become free, and some will become bound (total = bound + free).

See

for more.

Ben

And FWIW, when I've "standardized" bags of meta, I've found actual levels more like 36%.

And it'd be less if you use hot water or water with chlorine (so I've been told--does anyone know for sure if chlorine reacts with SO2) to dissolve your meta.

Dave

**************************************************************************** Dave Breeden snipped-for-privacy@lightlink.com

Greg, you can find campden in the form of k-meta too.

Man has been adding sulfur dioxide to wine for more than a thousand years. A large body of knowledge exists on the use of sulfur dioxide in wine and in many other food products. The benefits of using sulfur dioxide are well documented, and its positive effects are indisputable.

I think your reference to time may be somewhat exaggerated. It's positive effects are also relative to what you want to obtain. For most home-made wine makers you will find that they generally do not store their wines for more than 3-4 years. They keep it stored usually under constant conditions and in a fairly cool cellar (10 - 15 C). And they are fairly hygienic in the way they work with the must and wine (compared to commercial production).

There is a minimum of risk w.r.t. spoiling the wine under such circumstances. The SO2 mania is something which have caught on by home wine makers, not because of an experienced problem, but rather because there is a belief that they need to take on all the practices of commercial wineries.

David C Breeden wrote "Ben-And FWIW, when I've "standardized" bags of meta, I've found actual levels more like 36%. And it'd be less if you use hot water or water with chlorine (so I've been told--does anyone know for sure if chlorine reacts with SO2) to dissolve your meta."

David and others interested in SO2 reactions. Here is an excerpt from an article on the subject. A.J.DeLange is a well known scientist in beer brewing circles. A lot of beer makers use K Meta to rid local water of chlorine and chloramine.

bill frazier olathe, kansas usa

Date: Tue, 08 Apr 2003 14:25:19 +0000From: "A.J. deLange" Subject: Chloramine/ZincFor Doug: The reaction between chlorine and bisulfite is:S2O5-2 + 4Cl + 3H2O --> 2SO4-2 + 6H+ + 4 Cl-With mono chloramine it is:S2O5-2 + 2H2NCl + 3H2O --> 2SO4-2 + 2H+ + 2Cl- + 2NH4+In either case the bisulfite is oxidized to sulfate and the clorine, while it is not "removed", is reduced to chloride ion.This method of removing chlorine has been used by aquarists for years (though they use thiosulfate rather than bisulfite). With the advent of chloramine they must be sure to have an effective means of removing the ammonium ion/ammonia that is produced. It's a simple thing to check out. Draw a glass of stinky chlorinated or chloraminated water and drop in the corner of a Campden tablet. The chlorine smell will be gone very quickly (to be replaced, perhaps, with a sulfur dioxide smell so only use the tiniest bit of the tablet - one tablet should treat 40 gallons of water containing 3 mg/L chloramine.

David C Breeden wrote "And FWIW, when I've "standardized" bags of meta, I've found actual

David and others...I'm sure you know that K Meta degrades rather significantly over a years time. I buy fresh every year because of this...it's inexpensive and you have a better chance of adding the correct amount of SO2.

bill frazier olathe, kansas usa

If you read the section titled "3. Sodium and Potassium Salts" you'll see why K meta is quoted as 57% SO2. Potassium metabisulphite has the chemical formula K2S2O5 and a molecular weight of 222.4, and sulphur dioxide has the chemical formula SO2 and a molecular weight of 64.1. Each mole of the potassium meta salt will give 2 moles of SO2, thus the SO2 content of K meta is 2 x 64.1/222.4 = 57.6%.

This, of course, is the theoretical maximum SO2 yield from K meta. In practise, it can be lower as Dave has mentioned.

Dave: I've had similar experiences as you have with the strength of my meta. It just depends on the supplier (i.e. how it's been stored, etc). These days I always check my SO2 stock solutions to make sure they're up to strength.

Ben

Dad has been making wine for thirty plus years, and I don't think he even knows what SO2 is, or cares.

Fred

Thanks, Bill! That's really very useful!

Dave

William Frazier ( snipped-for-privacy@worldnet.att.net) wrote:

-- Dave

**************************************************************************** Dave Breeden snipped-for-privacy@lightlink.com