Amount — as I noted above, different sources recommend widely differing amounts. I follow the vendor recommendations, although generally speaking, with fining agents I use the least amount I believe will work. All fining agents have side effects, so using as little as possible minimizes the side effects.

I suspect kit vendors overdose with bentonite because it does not dissolve easily. Very few people will get the entire dosage to dissolve; most will drop immediately to the bottom of the primary.

Kits add bentonite during reconstitution for 2 reasons I know of: 1) The instructions are simpler when adding it up front when the fermenter is empty, to ensure enough dissolves. 2) The early addition starts clearing the wine faster, so the wine is more likely to be ready to bottle in 4 to 8 weeks.

Bentonite also eliminates protein haze, which was a problem in early kits.

Timing — In my example, I added bentonite post-fermentation because that was my need at that time. Next year, assuming I make Vidal again, I may add the bentonite pre-fermentation.

The timing of the addition depends upon the situation and the winemaker’s need.