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Bentonite Clay in Wine Making

Readers Write: The Case of the Missing Bentonite

An astute winemaker contacted me with a very pertinent question.


I did the Master Vintner Pinot Noir yesterday and was kind of surprised that there was no Bentonite. I thought that you had thought this was a good thing in kit winemaking. If not needed, please let me know.

Robb H


Excellent catch, sir. Yes, the kits I worked with previously had an addition of the fining agent, Bentonite, on day one. It's a common technique, done for a few reasons. But before we explore those, let's look at what Bentonite is.

Bentonite, named after the Cretaceous Benton Shale near Rock River, Wyoming is a type of clay, technically siliceous Montmorillonite, a smectite (clay mineral) formed when volcanic ash is washed of all of its larger particles until only a fine, soft, powder-like material is left. Because of its of absorbency and colloidal properties it's useful in a number of areas, like drilling mud, kitty litter and wine and beer fining.

It's particularly good at binding to unstable colloidal material and proteins, pulling them out of suspension. A colloid is a mixture in which one substance of microscopically dispersed insoluble particles is suspended throughout another substance. To understand this, picture your wine as a solution of all kinds of goo from the inside of a grape. There's sugars, tannins, flavor and aroma compounds and a lot of gums, pectins, proteins and colloids. These float around with a weakly positive electrical charge on them, kind of like what happens when you walk across a carpet in sock feet and get a static shock when your touch the light switch.

Bentonite Clay
Bentonite also has an electrical charge, but it's not only very strong, it's negative. Opposites attract, so bentonite particles sweep through the wine and when they encounter a bit of goo they bind straight to it, locking it in an electrical embrace. Together the two are too heavy to stay in suspension and they fall out onto the bottom of the vessel, packing down into a layer of clay and bonded proteins and colloids.

Since the juices used in some kits are not completely protein stable they need to be hit with a strong fining agent like Bentonite to keep them from being cloudy after fermentation. The easiest way to get it in was to put it in on day one and leaving it in until primary fermentation is over. There's also a small benefit to yeast health, as the particles of Bentonite act as anchor points for yeast cells to bud from, helping ensure a quick start to fermentation.

The juices used in Master Vintner Kits, on the other hand, are extremely protein stable. During crush, press and processing we make sure that unstable colloids and proteins are taken out of solution. They don't need any Bentonite, and where required, they have balanced yeast nutrients, which ensure that the wine ferments completely dry. Because we stabilize them in the winery before putting them in the kits, our wines clear brilliantly and beautifully, with minimal winemaking steps.

So there you have it: Robb, you successfully demonstrated Vandergrift's First Precept of Home Winemaking (Read The Instructions!) and seem willing to follow the second (Follow the Directions, Omitting No Detail However Small, Making No Change, However Slight)--good job! If you're as much of a Pinot Noir fan as I am, you're going to love your wine.

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  1. Bentonite
    Bentonite is a clay-like mineral that removes positively charged particles from wine. Add prior to primary fermentation to clear pectic and protein haze. Learn More
  2. Master Vintner® Wine Making Starter Kit - with Fermenter and Secondary

    Regular Price: $129.99

    Special Price $103.98

    Announcing a partnership of epic proportions—Master Vintner® and winemaking authority Tim Vandergrift have combined forces to bring you the ultimate winemaking starter kit. The Master Vintner® Wine Starter Kit is the most comprehensive winemaking starter kit on the planet—equipped with all the tools you need to make top-quality wine in a fraction of the time. The crystal-clear Big Mouth Bubbler® PET Fermentor instantly shows you how your primary fermentation is progressing. Graduated gallon markings give you accurate volumes without ever taking a measurement. The ported lid, sized to fit all your tools, lets you test, transfer and taste your wine during primary without removing the lid. A convenient punted bottom ensures you transfer clear wine from the get-go so you don’t have to fuss over clarifying later. Please note: when making 6 gallon kits that include wine skins, a larger fermentor must be used, such as the 7.9 gallon wine fermentor. Find our full line of Wine Making equipment here. Learn More
  3. Pinot Noir - Master Vintner™ Winemaker's Reserve™ Award Winning

    The exotic bouquet of Master Vintner® Pinot Noir captures luscious aromas of ripe red fruits and spiced chocolate in six gallons of hand-crafted wine. Rich flavors of cherry and tart raspberry merge with notes of dark, juicy currants and bright red strawberry to complement a luxurious, velvety mouthfeel. Pairs well with sharp cheese, pork, veal and salmon. Learn More
  4. Weekday Wine Making Starter Kit - Master Vintner®
    Your life moves pretty fast. So we worked hard to make Weekday Wine simple…Simple to create using our no-stress wine making starter Kit, and ridiculously easy to enjoy any day and any time that goes better with wine. And it’s a good thing the Weekday Wine Making Starter Kit is so simple to use. The Weekday Wine Starter Kit supplies all the fermenting equipment you need to make wine that’s perfect for pouring, any day of the week. Best of all we include your choice of wine recipe kit. Choose between the Cabernet Sauvignon and Chardonnay. Life is complex. Weekday Wine is simple. Kit Includes
    • Master Vintner™ 7.9 Gallon Fermenting Bucket x2
    • Drilled Lid for Fermenting Buckets
    • Auto Siphon for Transferring
    • Spring Tip Bottle Filler with Tubing
    • Herculometer™
    • Master Vintner™ Mini Corker and Corks
    • One Step - 8 oz.
    • Sodium Metabisulfite - 50g
    • Weekday Wine Recipe Kit : Chardonnay or Cabernet Sauvignon
    • Bottles are not Included, You will need 30 bottles
    Learn More

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