Question from Anna: Once in awhile I notice a dark coating on the sloped part of the bottle or dark sandy stuff in the wine. Does that mean the wine is bad?
Reply: Hi, Anna. Thanks for writing! It sounds to me like you’re describing sediment, something that occurs naturally in wine as it ages. It’s nothing to worry about at all. In fact, it may be a sign that the wine maker went easy on the processing which is usually a good thing.
As the wine ages, pigment and tannin get together get together to form a chain and become so heavy that, eventually, they fall out of the wine as sediment. This will happen sooner or later, depending upon how the wine was made. If the wine maker was quite thorough in applying clarification techniques such as fining and filtration it will probably take a long time for sediment to form. Perhaps it never will.
Some varieties are prone to throwing solids. I really notice it with Syrah. Quite often I notice a crust on the shoulder of the bottle and when I pull out the cork there’s gunky sediment on the end that stains my hands. Small price to pay for a delicious Syrah in my view 🙂
the sediment is gritty, so the thing to do if you have an older bottle of red to serve is to stand it up for several hours to let the sediment go to the bottom. Then, at serving time, carefully decant the wine (move it to another container – a decanter or pitcher) off the sediment and enjoy! If it’s quite old please be very gentle and wait to decant it until you’re ready to actually drink it. If it’s thinking about going over the hill the extra aeration may just give it a push.
Now, if you see sparkling crystals on the cork or in the wine, that’s a whole different kettle of fish: tartrates
I hope that helps! Thanks, again, for writing. Cheers!