Before filling an oak barrel with whiskey, wine, vinegar, or other liquids, it must be sealed properly. That means swelling the wood with clean water so that it expands and closes any tiny gaps between the staves. There are two safe and proven methods: cold soak and hot soak.
Method 1: Cold Water Soaking
Rinse the inside of the barrel 3–4 times with cool, clean water to remove any dust or wood debris.
Insert the spigot (tap) into the front hole by hand, then gently tap it with a hammer to secure it.
(If the barrel heads are made of glass, do not use a hammer — insert the tap firmly by hand only.)
Fill the barrel gradually:
Start by filling it about 1/3 with clean, cool water and let it sit for 3–4 hours.
Then fill it to 2/3 and wait another 3–4 hours.
Finally, fill it completely to the top and keep it full until any leaks stop.
🕒 Most barrels seal within 1 to 5 days, depending on how dry they are.
Once the barrel is sealed:
Drain the water through the bung hole, not through the tap.
Rinse it again.
Let it sit empty for about 1 hour.
Then fill it with your whiskey, wine, spirits, vinegar, or other liquid.
⚠️ Never drain a barrel through the tap — it may clog or get damaged.
Method 2: Hot Water Soaking
Hot water can seal a barrel faster but must be used with caution.
Rinse the barrel 3–4 times with cool, clean water.
Insert and secure the spigot by hand, then lightly tap with a hammer.
(If the barrel has glass heads, insert the tap firmly by hand only — do not use a hammer.)
Pour hot (steamy, not boiling) water into the barrel — about 25% of its total volume (e.g. 2.5L for a 10L barrel).
Insert the bung and gently rotate the barrel to slosh the water around, wetting the entire interior.
Stand the barrel upright to soak the tap-side head, then flip to soak the opposite head.
Remove the bung, turn the barrel upside down to drain it completely, and let it cool.
⚠️ Caution: Hot steam may force out the bung or spigot — always use gloves and avoid standing over the barrel.
After draining:
Fill the barrel with cool water and let it sit for a few hours.
If it still seeps, keep it full until fully sealed (typically 1–5 days).
💧 If soaking longer than 2 days, change the water regularly to prevent mould.
Final Steps
Once sealed and leak-free:
Drain the water through the bung hole.
Rinse one final time.
Let it air out for 1 hour.
Then fill with your preferred liquid (whiskey, wine, spirits, vinegar, etc.).
Storage After Filling
Store in a cool, shaded area (13–15°C / 55–59°F).
Maintain humidity between 70–80%.
Avoid direct sunlight, heaters, or drafts.
Do not overtighten the bung — allow for natural pressure balance.