What is the advantage of adding it to my wine on the first day?
We suggests that you add bentonite on the first day. The reasons behind it go beyond technology, straight into Wine Making philosophy. When bentonite is added on the first day, it disperses through the wine and most settles to the bottom within a few hours. At the end of 48 hours, however, the bentonite is back in circulation. This is because of the process of gas nucleation that the CO2 in the wine is undergoing.
As the yeast ferments the sugar, it converts it into carbon dioxide (CO2) and alcohol. The bubbles of gas don’t actually appear out of nowhere. They want to come out of suspension on some kind of a point, where a nucleus of gas can form the beginning of a bubble. The bentonite is surrounded by a bubble of gas and floats up to the surface of the wine. When the bubble bursts, the particle of bentonite drops back down to the bottom of the carboy, all the time working to absorb the particles that are clouding the wine. In this way, the bentonite is circulated around the wine continuously for days, doing its job.
When bentonite is added to a wine kit post-fermentation, it does not have the advantage of the CO2 lift that it would get during fermentation. Therefore the winemaker is obligated to stir it through the wine repeatedly, ensuring the thorough dispersal. In addition, because the bentonite will quickly settle out before it can effectively clear the wine, significantly more is needed when used post-fermentation. RJS Craft Winemaking kits typically use 10 or 15 grams of bentonite. Some other companies use up to 80 grams! This is far too much. Not only does this amount cause the formation of a deep, loose sediment bed; it also has the effect of stripping the wine.