SO2 Basics for Working Winemakers
A cellar-first refresher on what actually matters when you set sulfur targets.
SO2 decisions are rarely about one magic number. They are about the relationship between pH, microbial risk, oxygen exposure, and where the lot sits in its process timeline.
That is why strong wineries do not ask only, 'What is my free SO2 today?' They also ask what just happened to the wine, what is about to happen next, and how much protection the lot actually needs right now.
Keep these principles in your head
- Higher pH wines need more free SO2 to achieve the same microbial protection.
- A transfer, blend, filtration step, or packaging window can matter as much as the lab number itself.
- Target ranges should be tied to style and process stage, not copied blindly lot to lot.
- Consistent measurement discipline beats dramatic single corrections.
A better operating rhythm
Sample with intent
Know why you are measuring — routine monitoring, post-rack confirmation, pre-bottling protection, or microbial risk response all justify different urgency.
Calculate against pH and target state
Translate the desired protection level into an addition amount using current free SO2 and pH rather than relying on historical habit.
Recheck after disruptive operations
Transfers, filtration, blending, and packaging prep can change the risk profile quickly. Build confirmation checks into the workflow.
Common trap
The fastest way to over- or under-protect wine is to apply the same sulfur move to every lot because the cellar is busy. Standardize the process, not the exact number.
Use the product
Run the numbers before the addition
Use the SO2 calculator to set a target based on the wine’s current chemistry instead of reaching for a rule-of-thumb dose.