Copper sulphate

Daniele, I am not sure just what you mean by "safely." The label on my vitamin bottle says the "daily value" for copper is 2 milligrams. ATF allows 0.2 milligrams of copper per litter of wine. But 0.15 or so milligrams of residule copper often produce an ugly haze. Look here for more info

Daniele,

The following is excerpted from an earlier newsgroup post by Lum Eisenman, which I found by searching the newsgroup (via groups.google.com) for "copper sulphate":

"In my book, I recommend an addition of 3/4 milliliter of 1 percent copper sulphate pentahydrate solution in a 19 liter carboy. This addition will produce 0.1 milligrams of copper per liter of wine.

"This is an _extremely_ small dose. The "daily value" for copper is 2 milligrams, and if all the added copper remained in the wine (not possible), consuming 20 liters of wine at one sitting would not exceed the daily value. In many cases, a single 0.1 ppm dose of copper will completely eliminate the rotten egg smell. Little or no copper will remain in the wine _if_ the stench is still present after a small copper addition, and two or three additional

0.1 ppm doses can be added if necessary.

"ATF regs limit total copper additions to 0.5 ppm for commercial wines. I don't know why the limit is so low, but I would never add more than

0.5 ppm to any wine. Copper haze problems can develop at less than 1 ppm, and strange metallic taste problems often occur above 1 ppm."

Cheers, Richard

Thanks for the correction, Dave. I was looking at an older copy of the _FDA_ regs. I wonder if they correspond to the BATF regs now?

Free copper in wine also promotes oxidation later. If you don't have the lab equipment to accuratly determine the amount of copper to add to exactly neutralize the sulphide you are basically guessing. Way too much and you make poison wine. Slightly too much and you make wine that will not last. It's certainly possible to use it, but it's not a hit-or-miss sort of project.

One thing you might try is to rack the wine over a very clean copper scrubbing pad. You can boil a new pad a bit in vinegar to clean it well, then rinse it with plenty of water and shove it tightly into the bottom of a funnel. The sulphide will at least in part react with the copper surface and precipitate out on it. Little copper carries over into the wine. This, combined with the aeration that occurs during the process may help. At least it's worked a couple of times for me over the last several years.

--arne

Assuming I add the correct amount of copper sulfate to eliminate the H2S smell , would it help if I added some bentinite to the wine after adding the copper to aid in the removal of the Copper sulfide.

Daniele Galli

Daniele, Bentonite will not remove significant amounts of copper sulfide. But, copper sulfide is not soluble in wine, so it will come out of solution in any event. lum

After completing a smelling test I added 30 mils of 10,000 ppm coper solution to each 54 liter container and I think this works out to .0055 of a mil of copper per liter of wine.

How many milligrams of copper are there in a milliliter of copper ? I get the feeling i have over done it.

why do you divide by .2 and multiply by .5 to get the milligrams per liter ?