Stuff stuck to edge of bottle

[Kcwhippet]

Most of the tartrate crystals I've seen in red wine have been sort of pink - not clear and not red. Wine contains tartaric acid and potassium which combine and form potassium bitartrate. Not much can stay suspended in wine and a number of conditions can cause them to prcipitate out as crystals. The principal cause is cold temps. Once they precipitate out, they don't return to suspension if the wine warms up, so there may be more potassium bitartrate formed. The downside to this is that the wine will lose some of its acid and may start to taste unbalanced. Potassium bitartrate does have a usable function. Cooks call it cream of tartar, and it's actually a byproduct of the wine industry. Wineries that cold stabilize their wines sell their potassim bitartrate to companies who clean it up and package for sale to bakers.