Molecular SO₂ Calculator Chart
To ensure your wine is protected from oxidation and microbial spoilage it needs to have a molecular SO₂ of 0.8ppm. If the wine is dry (less than 2g/L residual sugar) then you can maintain the molecular SO₂ at 0.5ppm. This is a calculation based on the relationship between the Free SO₂ and the pH of the wine.
Conversely, if you are preparing a wine for tirage into sparkling, a high molecular SO₂ can inhibit the secondary fermentation. Understanding the importance of pH when adjusting your wines is crucial for quality. This guide is particularly for white wines and sparkling base wines. Red wine may behave differently, and you may not be able to maintain a high enough Free SO₂ and keep within the legal maximums, so some discretion is required.
Density/Ripeness Monitoring Comparison Chart
Accurate monitoring of the ripeness of your grapes is crucial to making harvest decisions. This chart provides a comparison of three ways to describe the sugar content/density including a conversion to Potential Alcohol % (PA).
Oechsle (Oe) and Brix are the two most commonly used descriptors in the UK. The accuracy of the conversion to PA% is not exact and also depends very much on the method used to measure the total soluble solids/density of the juice. This chart uses the calculation for PA% by Ribereau-Gayon.