Racking Wine: When, Why, and How

Racking is the process of transferring wine from one vessel to another while leaving the settled sediment (lees) behind. The French term is soutirage. It is one of the most routinely performed cellar operations and, done correctly, progressively clarifies the wine, removes sources of off-flavours, and allows controlled oxygen exposure.

Why Rack?

Wine accumulates sediment throughout its production:

• Gross lees after primary fermentation: dead yeast cells, grape solids, tartrate crystals, cell debris. This fraction is the most important to remove — autolysis (yeast self-digestion) from gross lees produces off-flavours: rubber, hydrogen sulphide, and "rotten egg" character.
• Fine lees after settling: mainly spent yeast cell walls and fine organic particles. Fine lees are more benign and some winemakers leave wine on fine lees intentionally (for autolytic character and texture — bâtonnage).
• Tartrate crystals: potassium hydrogen tartrate, which precipitates during cold ageing.
• Phenolic sediment: polymerised tannin-anthocyanin complexes that drop out of solution as wine ages.

Each racking removes these fractions and transfers clear wine to a clean vessel.

Racking Schedule

First racking — after primary fermentation

Timing: 1–2 weeks after primary fermentation is complete (gravity stable)
Purpose: Remove gross lees. This is the most time-sensitive racking.
What to leave: All visible sediment, any floating cap remnants (reds)

Gross lees should not remain in contact with wine for more than 2–3 weeks at cellar temperature. In warm conditions (above 18°C), move more quickly.

Second racking — after MLF (if performed)

Timing: Immediately after MLF is confirmed complete
Purpose: Remove LAB lees, which can produce off-flavours if left. Also an opportunity to check and adjust free SO₂.
What to leave: Fine lees (unless your style calls for lees ageing)

This is the moment to add the full post-MLF SO₂ dose. The wine is at its most vulnerable during this period — rack first, protect immediately.

Subsequent rackings — during bulk ageing

Timing: Every 3 months during barrel or vessel ageing
Purpose: Progressive clarification; controlled aeration (each racking introduces some oxygen); removal of continued sediment; monitoring

Wines aged in oak barrels are typically racked 2–4 times per year. Wines in sealed stainless tanks, with less oxygen exposure and less yeast activity, may need less frequent racking.

Pre-bottling racking

Timing: 1–4 weeks before bottling
Purpose: Final clarification; confirming the wine is clean and stable off its lees
Note: Leave adequate time after this racking for the wine to settle before bottling. A recently racked wine is sometimes "closed" — aromatically subdued for a week or two.

The Racking Process

Equipment

• Auto-siphon (spring-loaded, sanitised)
• 1–1.5m of food-grade silicone tubing (sanitised)
• Clean, sanitised destination vessel
• Campden tablet or weighed KMS powder
• Hydrometer and trial jar

Step-by-step

1. Sanitise all equipment before starting. The destination vessel, siphon, tubing, bung, and airlock all need to be sanitised.

2. Position vessels: Source vessel elevated above destination vessel to create gravity flow.

3. Insert the siphon gently into the source vessel. Position the siphon end 2–3cm above the visible sediment layer. Too low and you'll draw up lees; too high and you'll leave clean wine behind.

4. Start the siphon: prime the auto-siphon (pump handle 3–4 times), allow flow to begin.

5. Monitor the siphon end: As you approach the bottom, the wine begins to flow cloudy (drawing in fine lees). Stop when cloudiness begins. It's better to leave a small amount of clean wine behind than to rack in lees.

6. Transfer to destination vessel: Minimise splashing. A gentle flow at the bottom of the destination vessel is better than splashing from height (which introduces unnecessary oxygen).

7. Immediately add SO₂: Crush a Campden tablet and stir it in, or add weighed KMS powder.

8. Seal tightly: Fit bung and airlock immediately.

9. Discard the lees (or use in compost/garden — excellent soil amendment).

Handling lees for fine lees ageing

If you want to age on fine lees (sur lie): on the second racking, rack only the gross lees and leave a small amount of the fine lees in the vessel. Stir (bâtonnage) weekly or monthly to keep them in suspension. This contributes yeast autolytic character — brioche, cream, complexity.

Oxygen Management During Racking

Each racking introduces oxygen into the wine. This is sometimes desirable (to polymerise tannins, soften reds); sometimes not (for fresh aromatic whites or wines with insufficient SO₂ protection).

To minimise oxygen: Fill the destination vessel from the bottom (siphon end below the liquid surface), fill completely, and seal immediately.

To maximise oxygen (for reds needing softening): Splash the wine during the racking, allow it to flow from height. This is done intentionally at some wineries to achieve controlled oxidation.

Checking Yield Loss

You lose wine at each racking — the amount depends on:

• Volume of lees (first racking loses the most — 2–5% of volume typically)
• Vessel shape and size
• Whether you're racking off gross or fine lees

Keep records of what you transferred. Top up vessels after racking to minimise headspace. Use wine of the same batch, a similar wine, or inert gas (argon or CO₂) if you can't top up with wine.

Common Mistakes

Racking too late (gross lees): Autolysis begins. Off-flavours develop. First racking should happen within 2 weeks of primary fermentation ending.

Forgetting SO₂ after racking: The most common oversight. Racking exposes the wine to oxygen. Without immediate SO₂ addition, protection falls and oxidation begins.

Too much turbulence: Excessive splashing introduces dissolved oxygen, drives off CO₂ protection, and can cause oxidation or reduction artefacts.

Leaving significant lees in the vessel: Subsequent racking becomes harder as you keep diluting the lees rather than removing them cleanly.