🍷 Concrete egg
Also known as: concrete egg, egg-shaped concrete tank, concrete egg fermenter, wine egg, egg tank
An egg-shaped concrete vessel for fermenting and ageing wine, with smooth, cornerless walls.
A concrete egg (egg-shaped concrete tank, wine egg) is an egg-shaped concrete vessel in which wine ferments and ages. Inside it has no corners. The concrete is the same as in a concrete vat: it holds liquid in and lets oxygen through.
Proof for the shape itself is thin so far. In a 2025 lab study, Chardonnay fermented in glass flasks of four shapes, 800 millilitres each, at 16 to 17 degrees Celsius. In the round-bottomed flasks, including an egg-like one, the vigorous phase of fermentation ran faster than in the cylindrical or conical flask. The authors put this down to natural convection near the rounded base, but they did not measure it. And the flasks were glass, not concrete.
So the egg is a shape, not a separate material. Its wall is concrete with the same properties. In a Sauvignon Blanc trial, six months on lees in an uncoated oval concrete vessel of 450 litres gave a higher pH (3.38), lower acidity (6.42 g/L) and more iron than steel or clay.
Compare it with a stainless steel tank: steel lets in no oxygen and the egg lets it in slowly. Compare it with a concrete vat in general: the shape differs and the wall is the same. So the question of egg versus plain concrete is really about how the wine behaves inside, not about the material.
Facts
| Raw material | Concrete; the wall lets oxygen through but not liquid 3 |
|---|---|
| Acidity | Oval uncoated concrete, 450 L: pH 3.38, acidity 6.42 g/L 2 |
| Temperature | Lab flasks fermented at 16-17 C; round-bottomed ones had a faster vigorous phase 1 |
How it connects to Wine
🍷 Concrete egg → kind of → 🍷 Concrete vat → kind of → 🍾 Wine containers, glassware and serving → kind of → 🍷 Wine
Links
- Next step
- 🍷 Lees
- Part of
- 🍷 Concrete vat
Frequently asked questions
What is a concrete egg in winemaking?
An egg-shaped concrete vessel with no internal corners, in which wine ferments and ages.
Does an egg shape speed up fermentation?
In a 2025 lab trial round-bottomed flasks, including an egg-like one, sped up the vigorous phase compared with a conical one. Convection was not measured.
Does a concrete egg let air in?
Yes. The wall is concrete, and concrete passes oxygen though not liquid.
How is an egg different from an ordinary concrete tank?
In shape. The wall is the same concrete, so the difference lies in how the wine moves, not in the material.
Is it true that eggs always make better wine?
No. In a trial of four vessel types all wines were sound, and the differences were modest.
Sources
- Córdova-Palominos P. et al. The Impact of Fermenter Shape on the Performance of White Wine Alcoholic Fermentation and the Composition of the Resulting Wines in Laboratory-Scale Trials. J Food Sci 90(7):e70395, 2025
- Gil i Cortiella M. et al. Chemical and Physical Implications of the Use of Alternative Vessels to Oak Barrels during the Production of White Wines. Molecules 26(3):554, 2021
- Nevares I., del Alamo-Sanza M. Characterization of the Oxygen Transmission Rate of New-Ancient Natural Materials for Wine Maturation Containers. Foods 10(1):140, 2021