First of all, you should never add bentonite to a wine that hasn’t been given six months and three rackings to clear. If the wine still has not cleared, a bentonite treatment may be in order.
Bentonite must be hydrated before being used- Measure out the 1/2 teaspoon of bentonite. Pour 3/4 cup of boiling water into a small bowl (for 1 teaspoon of bentonite, use 1-1/2 cups of boiling water) and add the bentonite. Use a small whisk and mix the bentonite-water into a slurry. Mix for at least two minutes, working out any lumps that form. You want a creamy consistency. Cover and set aside for 24 hours. Do NOT skip this step! The bentonite will settle, so grab the whisk and whip it into a slurry again.
The wine should be racked recently before adding bentonite, as you do not want a lees deposit present when you add the slurry.
- Sterilize a wooden dowel or glass rod.
- Remove the airlock from the wine.
- While slowly adding the bentonite, use the dowel or rod to stir the wine.
- The bentonite has to be thoroughly mixed with the wine to work, so stir well.
- Clean the mouth of the secondary to remove any bentonite that may have gotten on it and refit the airlock.
- Keep the wine at room temperature (moving it into a cold garage will cause some of the bentonite to go back into suspension).
- The bentonite will attract positively-charged particles as it settles out.
- When the wine is clear, give it another few days and carefully rack it off the bentonite deposits.
- A treatment should take no more than two weeks. Store Bentonite in a cool dry place.