Concrete Egg Fermentation

It’s big, it’s egg-shaped and very concrete-looking.

You can’t help but notice the row of concrete tanks that now dominate the landscape of our winery at Flint. 

There're probably one of the few concrete eggs you’ll come across when touring English wineries because it’s still a little bit unusual. As are its larger squarer concrete cousins that sit alongside it.

Concrete is fascinating in winemaking.

Most people react to our concrete tanks with an “err isn’t that a bit old-fashioned?” Yes, it is a traditional method, and that’s the point - although our tanks are custom-made Italian modern mastery. 

Many earlier French and Italian wines were fermented in concrete before stainless steel became more available. Stainless steel is inert, easier to clean and (believe it or not) cheaper than concrete. It’s winemaking done by the text book. We use stainless steel where needed but also like to break the rules. 

Ben, Founder and Winemaker, says “concrete tanks are more impractical to use and difficult to clean than stainless steel, but the marginal benefits you gain make it worth putting in the time and effort”. 

Like oak barrels, concrete is porous which allows the wine to breathe, softening the tannins and allowing the wine’s aromas to transform. Concrete has a wonderful effect on the aromatics of our Fumé because Bacchus, the grape variety behind the wine, needs time and oxygen to open up.

But why an egg shape?

As well as being porous, the egg shape influences the circulation of the lees. Lees are the sediment from grapes or yeasts and are full of flavour and texture. 

“Lees ageing (sur lie) is a method where you deliberately leave the wine on its sediment,” explains Ben. “Bâtonnage is the process of stirring the lees to encourage even more flavour from these amazing particles. The egg is said to do the stirring for you as its shape means the lees don’t settle. The science is a little sketchy on how this works, but it’s a lengthy process requiring a bit of confidence that results in a wine with added complexity and softness.”

What are the results?

The Chardonnay that we put into the concrete egg back in 2024 spent eight months maturing and gained a delightfully soft biscotti tone from that natural bâtonnage. Half of it went into the 2024 Silex . We pushed the other half a little further for our Wine Club with 5 months in an amphora. We ended up with Labs 7, super bright and citrusy with a rounded texture from natural malolactic fermentation. 

Since then, we've been trialing Bacchus for the 2025 Fumé, and Pinot Gris from the 2026 harvest to see how the egg affects these varieties. You can guarantee we're always trying something new.