Agglomerated vs. Natural Cork: How Do They Impact Your Wine?

By: Matthew Marshall

Every wine lover knows the unmistakable pop of a cork being pulled from a bottle. That small piece of bark has safeguarded wine since the 17th century, thanks to the remarkable Cork Oak (Quercus suber). Grown primarily in Portugal, these trees don’t part with their bark quickly—growers must wait 25–30 years before the first harvest, and then only every nine years thereafter. Once stripped, the bark is carefully cut into whole corks for wine bottles. The remaining material? It’s given a second life, finely ground and reformed into “agglomerated” corks.

What’s the impact? The truth depends on the wine within the bottle.

Natural Cork

Crafted from a single piece of bark, natural cork is the time-honored choice and remains the benchmark for wines designed to mature gracefully. Its natural porosity allows a minute exchange of oxygen, encouraging structure to soften and complexity to evolve over time. For this reason, distinguished reds such as Cabernet Sauvignon or age-worthy whites like Chardonnay are often bottled under natural cork.

The drawback lies in that dreaded term: corked. Natural cork can harbor 2,4,6-Trichloroanisole, or TCA, a compound that imparts musty, wet cardboard-like aromas. Though harmless to health, it can compromise even the most prized bottle.

Best for: Those who prefer tradition
Pros: Exceptional for cellaring, conveys a premium image, biodegradable
Cons: Risk of “cork taint” (TCA)

Agglomerated Cork

Imagine a cookie cutter: the central cut becomes natural cork, while the remaining edges are transformed into agglomerated cork. The leftover bark is finely ground, sterilized, and bound with food-safe material to create a uniform closure. Virtually immune to TCA, these corks offer consistency and, in recent years, even precision—producers can select varying densities to influence oxygen transfer and, consequently, the wine’s evolution. While some may view it as less romantic than natural cork, agglomerated cork provides a sustainable and increasingly sophisticated alternative that places greater control in the winemaker’s hands.

Best for: Those who want to convey next generation winemaking techniques and want to greatly reduce risk of cork taint

Pros: Reliable performance, sustainable, minimal TCA risk
Cons: Some find the cork board-like visual less romantic

The Choice Is Yours

At The Wine Foundry, you have the option of bottling with either natural or agglomerated cork. Some value the heritage and elegance of natural cork; others prefer the precision and dependability of agglomerated closures. Neither is inherently “better”—the choice reflects the wine’s character and your vision as its steward. As always, our team is here to guide you toward the closure best suited to your wine.