The amount of SO2 needed to protect a wine is pH dependant: The free SO2 * levels required to protect wine are pH-dependent: as the pH goes up, higher levels of free SO2 are needed to protect the wine.This loss is coming from a binding phenomenon which needs to be taken into account and corrected for or our wines risk not being protected in spite of us making sulfur additions. Binding: Due to the complex way sulfite additions interact with the various chemical compounds and solids naturally present in our wines, the amount of free sulfite remaining in the wine after we make an addition often falls short of our calculated goal.

Here is the reason why: There are 2 technical concepts that need to be taken into account when making our sulfur additions or we run the risk of getting inaccurate results: As straightforward as this seems, however, accurate sulfite management is actually much more of a hands-on process than just adding a generic amount of SO2 from time to time and letting it ride. This is done by testing the SO2 levels in our wines at regular intervals and, if we are short of the desired range, by adding additional sulfur to make up the difference. Yet, for this protection to be effective, the required sulfite levels need to be consistently maintained at all times. This allows the wine to continue developing safely throughout its entire lifetime. When done correctly, maintaining the proper amount of sulfites in a wine protects it from oxidation and microbial contamination during ageing/storage. If we want to make high quality wines, then one of the most important things we as winemakers need to learn is how to effectively manage the sulfite levels in our wines. « Back to Articles Guide to SO2 Management and SO2 Calculator

Free so2 ph chart tor wine