A Simple Mead Recipe: Fining with bentonite

When I rack the mead from it’s primary fermenter to a 5-gallon carboy, it will throw off a deposit of mostly dormant yeast. To separate the mead from this sediment, or lees as it’s called, I’ll have to rack again in a month or so. Since I’m going to have to rack again anyway, I’ve decided to fine the mead at this step. Fining clarifies the mead by adding something that combines with suspended or dissolved solids then quickly falls to the bottom of the container. The “something” I’m going to add is called bentonite, a type of clay that’s very good at removing protein from mead. I’ve waited as long as three years for some mead to clear on its own, and still not been satisfied. Bentonite has worked for me every time.

Ready to measure bentonite with 150 ml water in a measuring cup, bentonite powder in a jar, and measuring spoons.

Bentonite is usually sold in powdered form, and you need to sort-of-dissolve (hydrate) it in water first. It doesn’t dissolve, but if you mix it into hot water and let it sit overnight, it will form a usable slurry. The way to do this is to measure the right amount, in grams, and use 10-20X that amount of water, in milliliters, to hydrate it. What’s the right amount? I’ve found that advice varies a lot. I use 0.5 g/L. Since I’m racking to a 5-gallon carboy and 1 gallon is about 3.785 liters, I need enough for about 19 liters – just under 10 grams. My problem is that I haven’t got a scale that’s accurate for such small quantities, so I use rules of thumb that say 1 tablespoon of bentonite weighs 11-12 grams. A tablespoon in 5-gallons works out to about 0.6 g/L, which is what I’ll use. I could try to get closer to my target of 0.5 g/L using a combination of teaspoons, quarter teaspoons, and so on, but the measuring errors would add up quickly.

So I boiled about 150 ml water in the microwave (about 2.5 minutes), added 1 tablespoon of the bentonite powder, and stirred.

It takes a good 20 minutes of stirring and scraping to turn clumpy wet bentonite clay into a smooth slurry.

And stirred, and stirred, and stirred. It got gooey and clumped. I scraped (with a knife- don’t use your fingers!) and stirred some more. It was thick. I added more water. When you do this, you will start to think that it will never work. But after 20 minutes of constant stirring (don’t stop). You will get a reasonably smooth slurry.

Pouring the thick but smooth bentonite slurry from a measuring cup into a jar.

After pouring it into a jar, I’ll let it sit overnight. I’ll give the jar a forceful twist, whenever I pass, just for good measure. Tomorrow, I’ll pour it into my sanitized carboy, along with a dose of sulfite, and rack the mead into it.

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3 thoughts on “A Simple Mead Recipe: Fining with bentonite

  1. Eric

    I’ve never used bentonite. I will admit to a batch that never clarified (even after a year).

    As long as I ferment with sort of fruit, with skin, the batches always clarify.

    I believe the tannins in the fruit skins do the same as the clay. They attract the particles and help them sink to the bottom.


  2. admin Post author

    Hi Eric,

    I’ve had the same experience when I ferment with fruit, and, like you, I think it’s the tannin thats doing the clearing.

    Boiling the honey-water mixture also works. It used to be pretty routine, but has become controversial in recent years. I may write about that in the future.


  3. Pingback: Washington Winemaker » Blog Archive » Making Mead: The controversy over boiling

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