Three Steps to Healthy Barrels
- Clean it.
- Sanitize it.
- Refill it, or treat it for empty storage.
Before a barrel can be sanitized for reuse or treated for storage, it has to be clean. Keeping wine within safe parameters won't protect you from an existing infection in a dirty barrel. Dirty barrels hold skins, sediment, tartrates, and microbes, dead or alive and shielded by the solids.
Cleaning wood is easy. Sanitizing it is extremely challenging, and wood is never truly sanitary. The best you can do is knock down the existing population and keep new growth from spreading, and preserve the wood if the barrel will sit empty.
New Barrel? Swell It First
When a new barrel arrives, it has to "soak up" water so the wood swells and seals itself. This is the French method:
- Stand the barrel on its head. Pour a few gallons of hot water over the outside of the head and a few gallons inside. The croze (where the staves meet the head) and every other seam and joint will swell and tighten.
- After 20 minutes, turn the barrel over and repeat.
- After 20 more minutes, put it on a rack, drain it, add back 3–4 gallons of very hot water and bung it. Let it sit for half an hour, then pull the bung. If you hear a "swoosh," it's most likely not a leaker.
- After 20 minutes, set it bunghole down on the rack and rinse the inside with a spray ball and wand.
- Let it drip dry for an hour, and you're ready to fill.
A slow barrel may need 24 hours full of water, hosed down now and then, before it seals completely.
Step 1: Clean
| Method | How | Our take |
|---|---|---|
| Barrel washing head (Aaquablaster LT or 360) | Driven by a pressure washer at 2,500–3,600 PSI and at least 4.5–5 GPM, like our KEW Poseidon 7. Hot water preferred (tolerates 180 °F). | A very, very good solution. Blasts tartrates off barrels and small tanks in 3–5 minutes. Great with a tankless water heater. |
| Steam | 3–5 minutes at 40 PSI: melts tartrates, opens the wood pores, releases old wine. Cool rinse after. | Good to great. Cleans and sanitizes. |
| Spray ball and wand | Low pressure, high flow, pump driven, no pressure washer. Can draw from a tank of chemical mix; also good for ozone or percarbonate sanitizing. | Basic. Slower and less effective, relies on hot water and contact time. |
| Hot water wash | Rinse until it runs clear, then drip dry or air dry for an hour or so. | The basic first step. Be careful with pressure washers: too much pressure up close can damage the wood. |
| Chemicals only | Skipping tartrate removal and relying on chemicals | We hate it. Chemicals don't mechanically clean wood, but they do strip good flavors. |
Watch the barrel washing head in action.
Step 2: Sanitize
- Ozone rinse after a hot water rinse, about 3 minutes. About ozone.
- Steam, as a cleaner and/or sanitizer. About steam.
- Sodium percarbonate soak (24–72 hours) followed by a citric acid rinse.
- Acid/SO2 soak ("pickling"): 3 lb tartaric acid (about pH 2.2) and ½ lb KMBS (about 500 ppm SO2) mixed in hot water in a 60-gallon barrel, topped and bunged, for 5 to 10 days.
Chemicals you may use (ask the seller for use and concentration):
- Caustic soda (sodium hydroxide) removes tartrates and works as a detergent. Follow with a cold water rinse and a citric rinse.
- Sodium percarbonate (sodium carbonate and peroxyhydrate) cleans, sanitizes and removes stains. Follow with a water rinse and a citric rinse.
- KMBS and citric acid ("sulfur/citric") makes a sanitizing rinse for tanks and equipment.
Please keep in mind you'll never remove every microbe from the porous wood of a barrel. It's simply impossible to bring a barrel to zero. We're not here to tell you a little of this or that isn't a flaw, or that some imperfection isn't part of a wine's style. But there's a difference between a small beauty mark placed by an angel and a major cosmetic affront. Beauty is in the eye, nose and mouth of the beholder. What you can do is sanitize an already clean barrel to control what lives there before the next fill.
Step 3: Preserve It, or Refill It
The best way to maintain a barrel is to keep it full of clean wine! If it has to sit empty, there are two ways to treat it for storage:
- Burn a sulfur wick or disk every 30 days, rehydrating the barrel each month as you re-gas it. A pleated paper cup over the bunghole keeps pests out and lets the barrel breathe. or
- Use EBX Barrel Protect: a natural tannin spray that protects empty barrels for up to three months, sulfur free.
While It's Full: Topping
Wine evaporates during barrel maturation, so top every 4 weeks. That's best.
- Unstack the barrels, inspect them, and rinse the outsides with hot water.
- Scrub around the bung with a 3 g/L tartaric acid solution, then rinse again.
- Pull the bung, look at the wine's surface and smell the headspace.
- Sample and check the free SO2. Add if needed and stir.
- Top with clean wine to the top of the bunghole.
- Put in a clean, sanitized bung and rinse everything again.
Rack and Return
Sometimes wine in barrel gets reduced and needs some air ("fresh" fruit instead of "canned" fruit character). Rack and return:
- Gather every barrel of the same lot. Sample, taste and smell each one for faults.
- Rack all the good barrels together into a tank. Now the lot is homogenized for flavor and aroma.
- Clean the empty barrels and let them drip dry. Change the barrel mix for the lot if you want to.
- Check the SO2, add if needed, and mix.
- Fill and bung the clean barrels.
- Save any extra wine for topping later.