How We Bottle Our Cabernet Sauvignon

Each spring, our winemaking and cellar teams prepare for bottling. Over the course of several weeks, they bottle our delicious Cabernets at our Napa Valley Winery and our Alexander Valley Winery. From 750ml bottles to the extra large (and extra rare) 18L bottles, every one is filled. It’s not your average assembly line, either. Each bottle is handled with extreme care, and the operation requires the labor of at least seven people at each winery. Here’s every step of the bottling line when set up for large format bottles.

Read A Quick Guide to Wine Bottle Sizing to learn about our various sizes. (Hint: Magnum isn’t the largest format wine bottle!)

Inspecting an empty wine bottle for defects

Step 1: Glass Quality Control

Using a light, we inspect each empty bottle for critical, cosmetic and label defects. Critical defects include cracks in the glass—weak points that can cause the bottle to break. Cosmetic defects include bubbles or marks. These don’t compromise the integrity of the bottle, but we want you to receive the best product—from wine to presentation. Our Napa Valley Cabernet Sauvignon bottle is silk screened, so the rare imperfection with printing is considered a label defect.

Quality control happens at every step, but glass inspection is among the first steps on a bottling day.

Nitrogen gas displaces oxygen in the large format bottles

Step 2: Sparging

To prevent oxidation of our wine, we use nitrogen gas to displace oxygen in the large format bottles.

The bottles are filled with filtered wine

Step 3: Filling

This is when the large format bottles are filled with wine. But to get to this stage (after two years of barrel aging), the wine is first thoroughly filtered.

The day before, the wine moves through crossflow filtration. This filtration step ensures that the wine is clean enough for the sterile membrane filter. On bottling day, the wine moves through a closed system from tank to the sterile membrane and into the filler bowl on the bottling line.

Levels in each bottle are adjusted to be uniform

Step 4: Volume Quality Control

We use tools like a fill height card to ensure the volume of wine in the bottle is correct. It’s all in the details, and we use transfer pipettes to adjust levels and make sure they’re uniform bottle to bottle.

Fun fact: The breakthrough method of “dry cork sensory screening” that Christiane Schleussner on our winemaking team developed with Cork Supply USA has given us one of the lowest cork taint rates on large-format bottles in the wine industry.

Corking a large format wine bottle of Silver Oak

Step 5: Corking

100-percent natural cork is used for all our bottles of wine.

After corks are applied, we also use the pressure gauge (pictured in Step 4) to check for optimal pressure. If there’s too much pressure in the bottle, the cork can be pushed out. If there’s too much vacuum in the bottle, the cork can be sucked down. We can make small adjustments to the bottling machine to optimize vacuum pressure within each bottle.

Foils protect the cork and are part of our packaging.

Step 6: Applying Foils

The foil, or capsule, on wine bottles were originally used to prevent bugs from eating away at and penetrating the cork. Now, foils are also seen as stylistic choice and part of our packaging.

Each wine bottle is wiped down and polished

Step 7: Polishing

As you would polish a trophy sitting on the top shelf, we wipe down each bottle with a cotton terry cloth. This is our last opportunity to perfect the presentation of the bottle.

Paper labels are precisely hand-applied to our Alexander Valley Cabernet

Step 8: Hand-Labeling

The paper labels for our Alexander Valley Cabernet are applied by hand. Precision is very important to ensure labels are uniform.

Numbering a large format bottle of Silver Oak Napa Valley Cabernet Sauvignon

Step 9: Numbering

Our 6L, 12L and 18L large format bottles are numbered, both on bottle and on box. There is a limited quantity each vintage, and every bottle is very special.

Stamping the bottling date onto the large format boxes

Step 10: Dating

Adjacent to the bottling line, the large format boxes are also stamped with the bottling date.

Plastic wrap protects the artwork on the large format Napa Valley bottles

Step 11: Wrapping

Due to the delicate nature of the silk screen label on our Napa Valley bottles, we wrap them in plastic wrap. This protects the art work.

For protection, large format bottles are secured in a wood box.

Step 12: Boxing

Once each large format bottle is wrapped, it is securely placed in a wood box. We also add Styrofoam for extra protection.

Each wine bottle is wiped down and cleaned

Step 13: Stacking

Each wood box is carefully stacked on a pallet. Pallets are sent into temperature- and humidity-controlled storage till its release. Here, the wine will be aged in bottle for an additional 20 months for our Napa Valley Cabernet and for an additional 14 months for our Alexander Valley Cabernet before it’s available to you on Release Day!

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