If you’ve been making your own fortified at home, you’ve probably heard someone mention SO2. Maybe you’re wondering why you need it, what it actually does, or whether it’s something only winemakers should worry about.
Here’s the good news:
SO2 is simple, effective, and one of the easiest ways to protect your barrel.
You don’t need a lab. You just need to understand the basics.
What Is SO2?
SO2 (sulphur dioxide) is like the quiet security guard of your wine. It:
• protects your blend from going stale
• keeps spoilage in check
• helps your wine age gracefully for years
It doesn’t change the flavour. it preserves it.
Why SO2 Matters in Fortified Wine
Your barrel breathes. That slow oxygen exchange creates beautiful layers of age, warmth, and complexity. But oxygen is a balancing act – and too much can cause your wine to taste flat or tired.
SO2 helps keep everything in harmony by:
• slowing down over-oxidation
• protecting against spoilage organisms
• supporting long-term ageing
• helping maintain brightness and depth
If you’ve ever tasted a barrel and thought “it feels a bit dull”, you’ve met low SO2.
Signs Your Barrel Might Need SO2
You might notice:
• the wine feels a little flat or stale
• the fruit and sweetness have faded
• the wine has dusty, thin or tired edges
• there’s a hint of VA or “nail polish” character
• the aroma feels muted
These are classic signs your barrel needs a small SO2 boost.
How to Add SO2 to Your Home Barrel
This is the part most people overthink… but it’s honestly very simple.
1. Measure the dose
Most home‐barrel additions are tiny — usually 1 to 2 grams of powdered or tablet form potassium metabisulphite (the most common form of SO2 for home use).
If you’ve received a recommendation from us through the Liquid Luxury Barrel Clinic, use that exact amount.
2. Add it to the barrel
Pull out the bung and put the powder of tablet straight into your barrel, pop in the bung, and give the barrel a gentle roll or sway to help it mix through.
It doesn’t need shaking or vigorous movement , just a little persuasion.
How Long Does SO2 Take to Work?
SO2 starts working almost immediately, but give it 24 hours for full protection.
That’s it. One day.
During that time it’ll:
• bind with any oxygen
• neutralise early signs of spoilage
• brighten and stabilise the wine
You won’t see anything happening — but you’ll taste the difference the next time you sample the barrel.
Can You Still Drink Your Wine?
Yes.
SO2 at these levels is completely safe to drink.
If you want the wine to be at its best, wait 24 hours after adding it before dipping your thief back in. This lets the SO2 settle into the wine and do its job properly.
If you have people coming over tonight and you’ve just added SO2?
Still safe. The wine will simply be in the early stages of protection.
The Bottom Line
SO2 isn’t scary, technical or complicated.
It’s simply one of the best tools you have to:
• protect your barrel
• revive tired wine
• support long-term ageing
• keep your fortified tasting vibrant, balanced and beautiful
Whether you’ve been running a home barrel for 20 years or you’re just starting out, SO2 is your quiet partner in keeping your blend in its best condition.
If you’re unsure how much your barrel needs, or you can’t tell whether your wine is tired or just going through a phase, bring a sample in.
Our winemaking team will guide you with a personalised SO2 rate and the ideal topping wine for your blend.