Bentonite is a negative charged, clay-like mineral that plays a crucial role in the winemaking process. Its unique properties allow it to remove positively charged particles from the wine, resulting in a clearer and more refined final product. The optimal time to use bentonite is during the late spring or early summer when the wine is at a warmer temperature. Additionally, its effectiveness is enhanced at lower pH levels, as the positive charge on proteins is stronger under these conditions.

To use bentonite effectively, it's essential to follow the correct procedure. For a generic low-level fining, mix 1/2 teaspoon (approx. 3g) of bentonite with 1/2 cup of hot water (140 to 200 F) in a blender for 1-2 minutes. Let the mixture stand for 60 minutes, then mix and stir it into the wine. Allow the wine to stand for 10-14 days before racking it off. This process will achieve fining at a rate of 0.16g/L.

For a mid-level addition, follow the same procedure but use 9 grams of bentonite with 3/4 cup of water. This will result in fining at a rate of 0.5g/L. However, for a more precise and scientific approach, it's recommended to create a stock solution of 5% bentonite and conduct bench trials to determine the lowest effective concentration. This is important because fining is a non-selective process, which means it removes not only yeast but also desirable phenolic compounds. Therefore, it's crucial to find the lowest concentration that will achieve the desired result.

To create a 5% bentonite solution, mix 50 grams of bentonite with 850ml of hot water and top it off to a final volume of 1L. Then, set up a trial with clear jars of the same volume and add different amounts of the solution to achieve addition rates between 0.3g/l and 2.0g/l. Let the trials clear overnight, and then evaluate the results. For more technical information on bentonite and its applications, there are many resources available.

When making a wine kit from concentrate, it's common to add bentonite on the first day for several reasons. Firstly, it serves as a nucleation site for the removal of CO2. Secondly, the bentonite is dispersed throughout the wine by the CO2, allowing it to be used more efficiently in a shorter time period. This results in a clearer and more stabilized wine with minimal waste.

In conclusion, bentonite is an essential tool for winemakers, offering a reliable and efficient method for removing impurities and clarifying wine. By following the correct procedures and understanding the optimal conditions for its use, winemakers can achieve exceptional results and produce high-quality wines that showcase their full flavor and character.