Wine Sediment: Crystals, Grit and How to Decant

Wine sediment is the natural deposit that collects in some bottles: dark grit in older reds, or small glassy crystals, often called wine diamonds, in whites and reds alike. Neither is a sign that the wine is faulty, and Wine Spectator’s Dr. Vinny says sediment isn’t harmful to drink. It just feels gritty. This guide explains the two kinds of sediment, why they form, and how to pour a wine off them.

Two kinds of wine sediment

	Grit and deposit	Tartrate crystals (“wine diamonds”)
Looks like	Dark grit, sometimes stuck to the side of the bottle	Clear or white crystals that can look like rock candy or broken glass
Made of	Grape solids, spent yeast, tartrates and phenolic (color and tannin) compounds	Potassium bitartrate, a salt of tartaric acid
Most common in	Red wines about 10 years old or more	Any wine, especially whites and wines that got very cold
Safe?	Yes, per Dr. Vinny	Yes, per Dr. Vinny
What to do	Stand upright, then decant	Leave them in the bottle when you pour

Sediment in red wine

Dr. Vinny lists what the deposit in a red wine is made of: tiny bits of grape solids, spent yeast cells, tartrate crystals and phenolic molecules, some of which give the wine its color. He puts the age when you are most likely to find it at upwards of about 10 years, though some young wines throw a surprising amount too.

Reds have more of it for a simple reason. In red winemaking, Dr. Vinny explains, crushed grapes and their juice are fermented together, so the wine picks up more solids and color compounds; red winemaking “simply lends itself to more sediment than white,” in his words. He also notes that the color often fades in older wines as sediment accumulates.

Sediment is not a quality problem. In a separate answer about a bottle from 1995, Dr. Vinny calls sediment perfectly natural for a red of that age, and perfectly safe to drink. In our view, a crust in a 15-year-old Cabernet is simply part of its age, not a reason to worry.

Note: Dr. Vinny’s point that young wines can surprise you is worth keeping in mind. In our view, it pays to pour the last glass of any bottle with a little care.

Tartrate crystals: what wine diamonds are

The glassy crystals at the bottom of a bottle or stuck to the end of the cork are tartrates. Dr. Vinny describes them as a harmless, naturally occurring byproduct of winemaking, made of the same stuff as the cream of tartar in your spice cabinet. People sometimes mistake them for broken glass, and wineries that remove them do so for cosmetic reasons, he says.

They come from tartaric acid, one of the natural acids in grapes. Virginia Tech’s extension enologist Bruce Zoecklein explains that tartaric acid and its salt, potassium bitartrate, are normal parts of wine. Potassium bitartrate dissolves in grape juice, but the alcohol produced during fermentation makes it less soluble, and cold lowers its solubility further. When a wine holds more than it can keep dissolved, crystals form and settle.

That is why crystals often appear after a bottle has been very cold. Dr. Vinny says extended cold exposure in storage, in transit, in a cellar or in a fridge can trigger them. Our guide to freezing wine explains why crystals often show up in wine that has been frozen and thawed.

Zoecklein also notes that when wine is chilled, tartrates drop out more quickly in white wine than in red, and in table wine more quickly than in dessert wine. Dr. Vinny adds that white wines are more likely to show tartrate crystals, while reds are more likely to have the darker deposit described above.

Why some wines have crystals and others don’t

Many wineries remove the excess tartrates before bottling with cold stabilization. The wine is chilled so the crystals form in the tank, where they can be filtered out, instead of in your bottle. Zoecklein describes it as the traditional method, along with ion exchange, and says crystals usually drop quickly during the first 12 days of chilling, then much more slowly.

Not every winemaker wants to do it. Dr. Vinny notes that some winemakers feel holding a wine at about 30°F for a few weeks can mute its aromas and flavors, so they skip the step. Among natural-wine producers, he says, crystals can be a badge of honor. Zoecklein points to a practical drawback too: wine held cold for long periods absorbs more oxygen, which can oxidize it. Crystals in your bottle simply mean the wine wasn’t cold stabilized, or wasn’t stabilized enough for the cold it later met.

In our view, wine diamonds are worth knowing about mainly so you don’t send a perfectly good bottle back. Dr. Vinny says they are safe to consume and don’t affect the wine’s flavor or aroma, though one might taste a little sour if you eat it.

How to get sediment out of your glass

You don’t need special equipment, but a decanter or any clean glass jug makes it easier.

1. Stand the bottle upright. Dr. Vinny suggests a couple of days before serving so the sediment settles to the bottom. A Wine Spectator collecting column on decanting an old Bordeaux recommends 24 hours. If the bottle lay on its side for years, some sediment may stay stuck to the glass, which is fine.
2. Open it gently. Try not to tip or shake the bottle. Dr. Vinny says there is no advantage to shaking a bottle of wine; mixing the sediment back in only makes it gritty.
3. Pour slowly with a light under the neck. The Wine Spectator column suggests a candle or, better, a flashlight shining under the neck, so you can watch the sediment move toward the opening. A phone flashlight works too.
4. Stop when the sediment reaches the neck. The column notes that about an inch of cloudy wine usually stays behind. We’d pour that last inch into a glass to settle and use it for cooking, or let it go.
5. Serve soon if the wine is old. The column recommends decanting an old wine no more than about 20 minutes before serving, because the aim is removing sediment, not adding air.

Tip: No decanter? Pour slowly straight into the glasses and leave the last inch in the bottle. A fine-mesh tea strainer or a piece of clean cheesecloth over a jug catches stray grit.

Decanting does two different jobs, and they pull in opposite directions. A young, tannic red benefits from time in a wide decanter to open up; an old red needs to be separated from its sediment and drunk fairly soon. In our view, the second job is the one that matters for sediment, and you don’t need a fancy shape for it. If you want one, our guide to the best wine decanter compares shapes and sizes, including models with a built-in filter.

Does sediment mean a wine has gone bad?

No. Sediment and crystals say nothing about whether a wine is sound. Dr. Vinny notes that you can’t tell just by looking at a bottle whether it was stored properly, and that even a well-stored old wine may simply not suit your taste. In our view, the only real test is to pour a little and smell it.

What does signal a problem is a smell or color that shouldn’t be there. A flat, nutty, brownish wine has taken in too much air (see our guide to oxidized wine), and a vinegar smell points to the bacteria behind a sour-tasting wine. Dr. Vinny lists a cork pushed out slightly, or signs of leaking, as warnings that heat or pressure got to the bottle. Those are the signs worth checking, not the deposit at the bottom.

Important: Sediment and tartrate crystals are normal. A vinegary or otherwise off smell is not. Don’t drink a wine that smells wrong, and if you have a health concern, ask your doctor.

How to keep sediment where it belongs

• Stand the bottle up a day or two before you open it, as Dr. Vinny suggests, so the deposit collects at the bottom rather than along the side. Our guide to how long wine lasts after opening covers what to do with the rest once the bottle is open.
• Avoid big temperature swings. Long, deep cold is what sends tartrates out of solution, so a bottle forgotten in the freezer or a car trunk in winter is a common culprit.
• Carry older bottles carefully. A bottle that has just been shaken in a bag needs time upright before it pours clear again.

In our view, a little sediment is part of drinking older and less processed wine. Give the bottle time to settle, pour with care and enjoy what is above it.