Found crystals in your bottle? Understanding wine tartrates
17 October 2026 · Vikipedia
Picture the scene. The wine arrives, you pour a glass and someone points to a few crystals at the bottom of the bottle.
“That’s gone bad, hasn’t it?”
The conversation about dinner stops. Suddenly everyone is a quality inspector. The person choosing by the label a minute ago has just been promoted to laboratory director.
Let’s take a breath.
What might be in that bottle?
One of the most common crystalline deposits is potassium bitartrate, a type of tartrate. It forms from components present in grapes and wine. These crystals do not themselves damage wine quality.
The name sounds rather more intimidating than the explanation. “Tartrates” will do. There is no exam before the main course.
Stabilisation before bottling helps prevent these crystals appearing later.
From the wine to the bottom: what precipitation means
A component can be dissolved in wine, invisible to us, and later form a solid. That transition is called precipitation. Here the word does not forecast rain over dinner; it describes some of the dissolved material becoming a deposit.
Cold encourages this process for potassium bitartrate. Cold stabilisation aims to make it happen under controlled conditions at the winery, before crystals reach the consumer. It is not a matter of removing everything “natural” from wine, nor can we deduce every treatment a bottle has received by inspecting its bottom.
Potassium and calcium behave differently
The AWRI also distinguishes calcium tartrate. Its formation is generally slower, and cold stabilisation is not effective at preventing it as it is for potassium bitartrate. “They chilled it, so no crystals can ever appear” is therefore too broad a conclusion.
You do not need to memorise two formulas. It is enough to understand that “tartrates” covers situations a winery may need to investigate separately. Identifying a deposit and deciding how to prevent it are related but different technical tasks. Recognising more than one possibility already avoids several confident diagnoses over dinner.
Neither an automatic failure nor a badge of authenticity
These crystals do not by themselves make wine bad. Nor do they prove it is better, more artisanal or more responsibly grown. Replacing “it is spoiled” with “it is wonderful because it has sediment” keeps the same faulty reasoning, just wearing a different team shirt.
Presentation and the quality we assess through tasting deserve separate attention. A producer may aim for a visually clear bottle; another may explain that certain deposits are possible. Either way, we still need information about the particular wine. The bottom of a bottle does not contain its complete production history.
What to do if it happens
First describe what you see without assigning a cause: “There is a crystalline deposit.” In a restaurant, ask for it to be checked; with your own bottle, keep its details and contact the winery or retailer. A photograph can start the conversation, but cannot replace technical identification.
Once tartrates are confirmed, careful pouring can leave the deposit behind. Decanting may be a serving option, not a treatment that repairs faulty wine. If the material is unknown or you suspect glass or other contamination, do not taste it to identify it: ask for an examination or a replacement.
There is no need to reproduce laboratory identification tests in your kitchen. We are answering a question about a bottle, not fitting a chemistry qualification between the bread and the main course.
Another visual puzzle concerns the tears running down a glass. Those involve a moving film of liquid; here we are discussing a solid deposit. Neither phenomenon awards tasting points.
So every deposit is normal?
Not quite. Not every deposit is a tartrate. Identifying an unknown one may require laboratory analysis; a photograph cannot establish exactly what a bottle contains.
That distinction matters. Reassuring someone without knowing would be just as unprofessional as condemning the wine without knowing.
If it happens, ask the person serving it or the winery. “What is this deposit?” is a much more useful question than “This wine is bad.”
The point is to understand what is in your glass. Dinner already involves enough decisions without adding a trial with no evidence.
Sources and review
Expanded and reviewed on 20 October 2026.