Bottling and corking like a cellar master: from the demijohn to the bottle on its side

By Magnus von Kageneck, cellar master (who he is) · As of September 2026

In a full, sealed bottle, wine is best protected from air; yeasts, bacteria and mold spores can no longer get in. The flip side: whatever goes wrong in the bottle, you can hardly correct any more. That is why bottling starts with checking, not with the hose.

Five questions before the first drop flows

If any answer is no, you wait.

1. Has fermentation finished? The zero mark of the Oechsle hydrometer stays submerged over several days, and a residual sugar test finds no sugar or hardly any (Measure, don't guess). If the hydrometer stays clearly above zero, fermentation is stuck; then the emergency plan is what helps, not the bottle.
2. Is the wine clear, and will it stay clear? If it throws new sediment, fine or filter it first (more on clarifying).
3. Is it protected? Before bottling, it should contain 30 to 40 mg/l of free sulfur dioxide, measured with the free sulfur dioxide test kit. Its description gives lower target values; I work with 30 to 40 mg/l for every wine. For red wine, subtract 10 to 15 mg/l from the reading. Without a measurement, add no more than 0.5 g of potassium metabisulfite per 10 liters (Sulfiting without fear).
4. Will a sweet wine stay still? Below 15 % vol, a wine with residual sugar or one sweetened afterwards first gets potassium sorbate: 2.6 g per 10 liters, weighed on a precision scale and added to the clear, sulfited wine. That is both the maximum and the working amount, so do not use noticeably less. At 15 % vol and above without sorbate, the wine has to pass the fermentation test (Stopping fermentation and sweetening).
5. Do you have enough ready? 10 liters of wine fill about 13 bottles of 0.75 liters.

For the fermentation test, fill a plastic bottle with the wine, close it and stand it in a bowl at 20 to 25 °C for one to two weeks; the demijohn stays under its airlock in the meantime. If the bottle becomes taut and hard, the yeast is still working; in glass, the cork would shoot out or the bottle would burst. In that case, let the wine ferment out completely, clarify it and sweeten it again, this time with potassium sorbate.

Anyone who deliberately lets wine referment in the bottle is making sparkling wine. That only works in pressure-resistant sparkling wine bottles with stoppers and wire cages, and with no more than 24 g of sugar per liter, everything included.

Bottles: clean is enough, low in germs is possible too

Brown glass blocks light best, green less so, clear glass hardly at all; under light, an off-flavor develops over time. Wine in clear glass belongs in a box or a dark cellar.

A bottle does not have to be sterile, because the hose, the cork and the wine are not sterile either; it does have to be mechanically clean. Soak used bottles for about a day in 5 to 10 g of cleaning concentrate per 1 liter of water, no warmer than about 50 °C. Brush them out inside, rinse until nothing foams any more and let them drain upside down. Discard any that smell musty or of vinegar, or that have cracks at the mouth. The alkaline solution attacks skin and eyes: wear gloves and safety goggles. A difference of more than 30 °C between glass and water can shatter a bottle.

Low in germs with a sulfite solution

For a sulfited wine, a clean bottle is usually enough. If you want more, rinse shortly before filling with 40 g of potassium metabisulfite per 1 liter of cold water. The salt releases about half its weight as sulfur dioxide (SO₂), so here 20 g per liter. That is twice as strong as the “2 percent solution” of 1 g in 50 ml that some packs mention; their 2 % refers to the salt.

Do not add acid: it drives out additional sulfur dioxide, which burns the eyes and airways.

1. Make up the solution with the window open, in a container that has never held acid. Wear safety goggles and gloves.
2. Pour 20 to 30 ml into a bottle, close the mouth with your gloved thumb and swirl until the inside wall is wetted. Turn your face away while you do this.
3. Pour the portion on into the next bottle; it is enough for two. Let the bottles drain well upside down, because any drops left behind end up in the wine as sulfur. Fill them no sooner than 15 minutes and no later than 3 hours afterwards.
4. Keep the rest closed in a labeled container, never in a drinks bottle, and pour it away with plenty of water after bottling.

Potassium metabisulfite carries the signal word “Danger” and the statements “Causes serious eye damage” and “Contact with acids liberates toxic gas”. Anyone with asthma should leave this step to someone else. Store the powder separately from the yeast nutrient salt; the two white powders are easily mixed up.

Filling without air or sediment

The day before, set the demijohn up high so that any stirred-up sediment settles; the bottles go lower down. In the siphon set, a racking cane passes through a two-hole stopper and ends a few centimeters above the sediment. A small tap just before the end of the hose shuts off the flow when you change bottles.

A dry attachment packed with filter wool sits in the second hole. To start the flow, open the tap and blow gently through the attachment, so no unfiltered breath reaches the wine; after that, the wine runs downhill on its own. An airlock filled with liquid is no good for this, or you will push the liquid into the wine. Sucking on the hose with your mouth is unhygienic; a wine siphon with blow-in start gets the flow going without sucking.

1. Lead the hose almost to the bottom of the bottle. The wine rises from below and pushes the air ahead of it instead of stirring it in.
2. If the hose does not reach that far down, hold the bottle at an angle and let the wine run down the inside wall.
3. Slowly raise the hose as the wine rises and close the tap at the right fill level.

Headspace: 1 to 2 cm of air under the cork

Wine expands as it warms up. A table wine at 12 % vol, bottled at 10 °C, gains 2.6 ml in the 0.75-liter bottle by the time it reaches 25 °C. One centimeter of bottle neck with an internal diameter of 20 mm holds about 3.1 ml:
3.14 × 1 cm² × 1 cm = 3.1 ml

Filled to the brim under a crown cap or screw cap, the bottle can burst; a natural cork is slowly pushed out by the wine, and the bottle leaks. So leave 1 to 2 cm between the bottom of the cork and the wine if you fill at 15 to 20 °C. Move cellar-cold wine into a warmer room the day before.

A cork held against the outside of the neck, flush with the rim of the glass, shows you the fill level: 1 to 2 cm below its lower end.

Setting the cork: 23 mm into an 18-mm mouth

The usual wine bottle is about 18 mm wide at the opening and 20 to 21 mm inside. Corks for it therefore have to be at least 23 mm thick, otherwise wine creeps along the cork and air gets in. A corker compresses the cork to around 16 mm and pushes it into the neck in one stroke, where it expands again. Cork, corker and mouth have to match.

Plastic T-top stoppers let more oxygen through and are only suitable for bottles that will be opened soon. How to prepare corks is stated on their pack, and that takes precedence. Insert coated corks dry or briefly moistened, because long soaking can bring in germs. Only hard, uncoated natural corks are soaked for 10 to 20 hours in water no warmer than 30 °C; hot water makes them brittle. Corks become low in germs with a brief dip in the sulfite solution.

1. Stand the bottle on a non-slip surface and place the corker with the cork squarely on the mouth.
2. Press both levers down briskly and evenly as far as they will go. That way the air escapes from the neck before the cork expands.
3. The cork sits flush with the rim of the glass. If it is crooked, use a new one.
4. Leave the bottle standing upright for at least five minutes, then lay it down.

Caution: if you press the levers too slowly, air stays trapped in the neck and presses on the wine. Then the cork springs back out, or the bottle bursts. Use only bottles without cracks and wear safety goggles.

Capsule on, bottle down

The cork moth lays its eggs on corks; the caterpillars eat tunnels into them, and the cork starts to leak. So right after corking, pull a close-fitting capsule without holes over the neck. An aluminum capsule is put on loosely; a spiral ring pulled over it presses it firmly around the mouth.

Store bottles with natural corks lying down, because a moist cork keeps out air better than a dried-out one. Bottles with plastic stoppers stand upright. The room should be cool, dark, at an even temperature and frost-free (getting the cellar ready for winter). If it smells of paint or heating oil, the cork takes on the smell and passes it on to the wine.

What goes on the bottle

Write on every bottle what is in it, when you filled it and under which number the batch is recorded in your cellar book. If a bottle leaves the house, fruit wine carries the name of its fruit, so apple wine rather than wine, and the label states the alcohol content and “contains sulfites”.

Safety note: Potassium metabisulfite and potassium sorbate are hazardous substances. Potassium sorbate carries the signal word “Warning” and the hazard statement “Causes serious eye irritation”; wear safety goggles and gloves when weighing it out. The label of the product supplied is what counts, including for the cleaning concentrate.

Magnus von Kageneck is the cellar master character of Maischewerk. The texts in this series are written with the support of artificial intelligence and are checked for technical accuracy before publication.

Related in the shop: Making Wine and Kitzinger Original