Walk into a proper wine cellar and it’s like walking backstage at a three-star restaurant mid-service. It looks calm, almost monastic. But behind that quiet? Constant maintenance, tiny rituals, a thousand little acts of paranoia. One of the least glamorous, most important of those rituals has a dull little name: topping up.

Not sexy. Not romantic. No Instagram filter. But if you like your wines clean, alive, and not smelling like a wet mouse died in a cider barrel, you should care. Because topping up is the cellar-world equivalent of changing the oil in your car or sharpening your knife. Skip it, and everything goes to hell faster than you think.

What “Topping Up” Actually Is (And Why Anyone Bothered)

Topping up is simple on the surface: you add wine to a barrel, tank, or bottle to bring the liquid level up so there’s as little air as possible.

That’s it. No mysticism. No poetry. Just filling the damn thing so oxygen doesn’t sit on top of the wine, slowly turning it into vinegar or something that tastes like your grandparents’ forgotten sherry.

But like a lot of “simple” things in food and drink, the devil is in the details. And the devil, in this case, is oxygen.

Wine is a living, breathing, sulking teenager of a thing. It changes. It reacts. It throws tantrums. Give it too much air and it oxidizes—browns, flattens, loses fruit, picks up bruised-apple and nutty flavors you didn’t ask for. Give it just a little, under the right conditions, and it can become complex, structured, layered. The line between “beautifully evolved” and “this tastes like stale cider and regret” is thin.

Topping up is how winemakers walk that line without face-planting.

The Enemy Above the Wine: Headspace and Oxygen

Here’s the problem: wine evaporates. It seeps. It gets soaked into the barrel staves. It disappears like a chef’s stash of staff-meal beer. That vanishing act creates what winemakers call headspace—the gap between the top of the wine and the closure (bung, cap, cork, whatever).

That headspace is a tiny pocket of air. And air is mostly oxygen. Oxygen is both friend and assassin.

• In tiny, controlled doses: It helps tannins soften, aromas develop, and the wine grow up a bit.
• In bigger, uncontrolled doses: It wrecks the wine. Oxidation. Bacterial growth. Off-flavors. The liquid equivalent of leaving a sliced apple on the counter for two days.

So topping up is the constant game of “don’t let that headspace grow.” Keep the wine as close to the top as possible. Minimize the air. Minimize the risk. Let the wine evolve, not rot.

Angels’ Share: The Romantic Term for “Your Wine Is Disappearing”

If you’re aging wine in barrels, you’re losing some of it. Always. Evaporation. Absorption. A little goes into the wood. A little escapes through the pores. Winemakers call this the angels’ share because apparently it sounds better than “the universe is drinking your profit.”

Over months in barrel, that loss is not nothing. Levels drop. Sometimes a couple of centimeters. Sometimes more, depending on humidity, temperature, and the barrel itself.

That drop creates headspace. Headspace invites oxygen. Oxygen invites trouble. So winemakers top up their barrels regularly—every couple of weeks, every month, depending on the style and the paranoia level of the person in charge.

They keep a stash of the same wine (or something very close to it) in tanks or other barrels specifically for this purpose. They open the barrel, pour or pump in enough wine to bring the level back up, close it again. Over and over, for as long as the wine’s in wood.

Like refilling the fryer oil. Not glamorous. Absolutely essential.

What Winemakers Use to Top Up With

This is where things can get interesting—or sketchy.

In a perfect, well-behaved, textbook cellar, you top up with:

• The exact same wine, same vintage, same lot.
  This keeps everything consistent. No weird blending, no flavor surprises. Just putting back what time stole.

But reality is messy, and cellars are full of compromises. So sometimes:

• Same vineyard, same year, different barrel.
  Close enough. The house blend will smooth it out.
• Same grape, same region, same vintage, different parcel.
  Now you’re blending in micro-doses. Usually fine, sometimes even adds complexity.
• Neutral wine from a similar style.
  In big operations, there might be a “topping wine” that’s deliberately simple and compatible.

In serious, quality-focused wineries, topping wine is treated like a sacred ingredient. Nobody wants to screw up a great barrel by topping it with something that tastes like a discount bin.

In cheap, industrial setups? If you’re paying $4 for a bottle, nobody’s losing sleep over the nuance of topping fractions.

How Often Do They Do It?

It depends on a few things:

• Type of vessel

  • Barrels: commonly topped every 2–6 weeks.

Think of it like checking your mise en place. The more demanding the service, the more often you check.

Topping Up vs. “Letting It Ride” (Oxidative Styles)

Not all wines are topped up. Some are deliberately not topped, on purpose, to create oxidative styles.

That’s where you get:

• Sherry (especially Fino and Amontillado)
  Barrels are not filled to the top. The space above the wine lets flor yeast form a film on the surface. That yeast protects the wine from full-on oxidation while transforming it into something salty, nutty, and weirdly addictive.

• Traditional Vin Jaune from Jura Similar idea. Wine ages under a veil of yeast, not topped up, for years. You get curry, walnut, spice, and “what the hell is this and why do I want more?”

So topping up is not a universal law. It’s a choice. Most wines are protected from oxygen with religious devotion. A small, eccentric group is raised with oxygen as a co-parent.

The Biology in the Shadows: What Happens If You Don’t Top

Skip topping up in a “normal” wine, and a whole cast of microscopic miscreants shows up:

• Acetic acid bacteria
  These guys love oxygen. They turn your wine into vinegar. Literally. That sharp, volatile, nail-polish-remover smell? That’s them saying hello.

• Oxidative yeasts
  They can form films, chew through remaining nutrients, and make the wine smell like bruised apples, stale beer, or damp cardboard.

• Brettanomyces (Brett)
  Not strictly about topping up, but oxygen management plays into it. Brett can turn your nice red into something that smells like a barnyard, Band-Aids, or a wet dog that rolled in a tire fire. A little can be “interesting” to some people. A lot is a crime.

Topping up is one of the physical, hands-on ways to keep these critters in check. Not a silver bullet, but part of a bigger hygiene and oxygen-control strategy.

Topping Up in Tanks and Bottles

Barrels get all the attention, but topping up matters in other places too.

In Tanks

Modern wineries use stainless steel tanks that can be:

• Closed and inert
  You can blanket the headspace with inert gas (nitrogen, CO₂, argon) instead of topping with more wine. Same idea: keep oxygen away.
• Variable-capacity tanks
  These have floating lids you can lower right onto the surface of the wine, then seal. It’s like topping up without adding more liquid.

Still, when tanks aren’t full, some winemakers will top them with wine, or at least gas, to keep air from sitting on the surface like a vulture.

In Bottles

Once wine is bottled, “topping up” becomes a question of fill level—how much space is left between the wine and the cork or cap.

That space is called ullage. Too much ullage over time, especially in old bottles, means more oxygen exposure, more risk of oxidation. Collectors obsess over this. Low fill on an old bottle? Red flag. It’s like seeing a steak that’s been under the heat lamp for three hours: proceed with caution.

Natural Wine, Low Intervention, and the Topping Dilemma

In the low-intervention / natural wine world, topping up can get political.

• Some producers top up religiously but avoid SO₂, relying on careful hygiene, cool cellars, and tight oxygen control.
• Others let levels drop more than conventional wisdom would like, aiming for more “alive,” oxidative, or wild expressions.

When it works, you get wines with layers: bruised fruit, nuts, spice, funk—in a good way. When it doesn’t, you get mouse taint, vinegar, and a bottle that tastes like a science experiment abandoned in a squat.

The good ones are just as obsessive about topping up as any classic Bordeaux château. They just have a different set of lines they refuse to cross.

What This Means for You as a Drinker

You’re not topping barrels in your basement (probably). So why should you care?

Because topping up is one of those invisible practices that separates:

• Clean, age-worthy wines from
• Flawed, prematurely tired, or straight-up spoiled wines

If you’re into:

• Fresh, precise whites
• Structured, cellar-worthy reds
• Champagnes and sparkling wines that age gracefully

then you’re into wines made by people who take topping up seriously.

If you’re exploring:

• Sherry
• Jura vin jaune
• Oxidative whites
• Certain natural wines

then you’re stepping into a world where not topping up might be part of the style. The nutty, savory, salty, or wild character you’re tasting? That’s what happens when oxygen is invited to the party instead of kept outside behind the rope.

The Unsexy Art That Keeps Wine Alive

In kitchens, the great dishes aren’t just about the final flourish on the plate. They’re about the grind: stocks skimmed, sauces reduced, knives honed, stations cleaned, prep done right. Nobody posts that on social, but without it, service falls apart.

Topping up is the cellar version of that grind. No romance, no spotlight. Just a winemaker, a hose or a bucket, a barrel, and the quiet knowledge that if they stop doing this tedious little task, their precious wine turns into a cautionary tale.

So the next time you’re swirling a glass of something beautiful—clean, balanced, alive—remember there’s a whole world of invisible work behind it. Someone walked into a cold, damp cellar a hundred times, checked levels, pulled bungs, added wine, sealed it back up. Again and again.

All so you’d never have to think about it.

But now you know. And once you know, you can’t unsee it: wine isn’t just fermented grape juice. It’s constant, obsessive maintenance. Topping up is one of the smallest, least glamorous, most essential moves in that whole dance.

The wine you love? It’s still here, still itself, partly because someone was stubborn enough to keep filling the damn barrel.