As you’ve probably read in my columns and in the Winemaker’s Answer Book, though I like to “let wine be what it will be,” when it comes to potentially toxic things like high residual levels of copper, I like to only add — when I really have to — in measurable amounts. Though admittedly it sounds more romantic, traditional and “natural” to pass wine through a copper pipe in order to prevent or treat hydrogen sulfide (H2S- which I think is what you mean when you wrote SO2 above), when it comes to copper, I like to use my pipettes to dose in a 1% liquid solution (which can be purchased from wine lab supply companies). I don’t want to panic you into thinking your wine is poisoned; you probably are fine, especially since copper will frequently bind up and drop out of solution to the bottom of your aging vessel over time. In my commercial winemaking life I am bound by foreign exporting rules for maximum residual copper limits, so I’ve just gotten into the habit of measuring out copper if I need it rather than just “guesstimate.” It’s like actually measuring out your tartaric acid instead of just adding it “until the must tastes right.” You can do the latter, it’s simply more efficient and accurate to use the former. You’re correct in mentioning that wine is different than water; because of its low pH and high alcohol, it is a much stronger solvent than water and will more quickly dissolve copper. Because of all this uncertainty, I choose to measure my copper additions.
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