🍷 Concrete vat
Also known as: concrete vat, concrete tank, concrete fermenter, concrete vessel, concrete cistern
A thick-walled concrete vessel for fermenting and ageing wine that holds liquid in but lets a little oxygen through.
A concrete vat (concrete tank, concrete fermenter) is a thick-walled vessel for fermenting and ageing wine. Concrete holds liquid in but lets in oxygen from the air, so the wine breathes slowly, as in an oak barrel, only without the taste of wood.
Spanish researchers measured how much oxygen gets through. For two types of concrete with a wall of about 10 centimetres, treated with tartaric acid, the figures were 56 and 88 cubic centimetres per square metre a day, more than the average barrel. After a week in wine, permeability drops, by 88 percent in one sample. An epoxy coating all but stops oxygen, and the authors say claims of near-zero oxygen should be disregarded unless such a coating is used.
There is a downside: the wine's acid eats into concrete. In a Sauvignon Blanc trial, six months on lees in an uncoated oval vessel of 450 litres gave the highest pH (3.38) and lowest acidity (6.42 g/L), with about five times as much iron as in the other vessels. Concrete used to be lined with tartaric acid, later with inert resins. Today some producers go back to it bare.
Next to a stainless steel tank, concrete differs in that it breathes. Next to an oak barrel, it adds no oak notes. Its closest relative is the concrete egg, only in a different shape. Even so, in that trial all four wines turned out perfectly sound.
Facts
| Raw material | Concrete; test samples about 103 mm thick 1 |
|---|---|
| Main use | Fermenting and ageing: holds liquid in, lets oxygen through 1 |
| Hardiness | Uncoated, wine acid attacks concrete: iron ~2.45 mg/L, pH 3.38 2 |
| Bottle size | Oval concrete vessel in the trial: 450 L 2 |
How it connects to Wine
🍷 Concrete vat → kind of → 🍾 Wine containers, glassware and serving → kind of → 🍷 Wine
Links
Frequently asked questions
Does a concrete tank let in oxygen?
Yes. Concrete can be impermeable to liquid yet pass oxygen from the air: 56 and 88 cm³ per m² a day in one set of measurements.
Why was concrete lined with tartaric acid or epoxy?
Tartaric acid formed a calcium tartrate layer, later replaced by inert epoxy resins. Epoxy nearly stops oxygen.
What happens to wine in bare concrete?
In one trial the pH was highest (3.38), acidity lowest (6.42 g/L) and iron about five times higher.
Why do some producers skip the lining?
The tartrate layer is hard to clean and epoxy may release compounds, so some use bare concrete.
Is it true that concrete is airtight?
No. The authors say claims of negligible oxygen should be disregarded unless a special coating is applied.
Similar
🍷 Wooden vat · 🍷 Canned wine · 🍷 Demijohn · 🍷 Bag-in-box · 🍷 Wine in carton · 🍷 Stainless steel tank
What it includes
Sources
- 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
- 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