Champagne Cellars Were So Lethal That Workers Wore Iron Masks Against Exploding Bottles

A bottle of champagne holds roughly six atmospheres of pressure, about three times what a car tyre carries. That force is the whole point of the wine, and today it is routine to contain it. For much of the nineteenth century it was not. The pressure that gives champagne its sparkle also made it, for decades, one of the most physically dangerous products in the world to manufacture, and the men who worked in the great cellars of Champagne wore iron wire masks to keep flying glass out of their faces.¹

The problem had a name in the trade: la casse, the breakage. And for a long time nobody could reliably stop it, because nobody could measure the thing that caused it.

Where the pressure comes from

Champagne gets its bubbles from a second fermentation that happens inside the sealed bottle. A finished still wine is bottled with a small dose of sugar and yeast; the yeast eats the sugar and gives off carbon dioxide, and because the bottle is closed, the gas has nowhere to go. It dissolves into the wine under mounting pressure until, by the end, the bottle holds several atmospheres of it.² Open it, and the pressure escapes as foam and a flying cork.

That is the design working as intended. The trouble was that the amount of pressure depended on exactly how much sugar was in the bottle when it was sealed, and in the early nineteenth century no one could say precisely how much sugar a given wine already contained or how much more to add. A little too much, and the fermentation drove the pressure past what the glass could bear.

La casse

When a bottle failed, it did not crack — it burst, throwing glass across the cellar at speed, and a single explosion could set off its neighbours in a chain, so that a rack of bottles went one after another. The losses were staggering. In the cellars of the 1840s a maker could normally expect to lose something like ten to twenty per cent of a cellar to breakage, and in a bad year an entire cuvée could be destroyed: a whole blend gone to shards and spilled wine.¹

For the people who worked in those cellars, the danger was physical as much as financial. Flying glass maims and kills, and the cellar hands who turned and moved the bottles worked in the middle of it. They wore masks of iron wire mesh and heavy gloves, and even then the work was hazardous; one nineteenth-century writer warned that it was not wise so much as to cross a champagne cellar without the protection of a wire mask over the face.¹

It was not wise to cross a champagne cellar without a wire mask over your face. In a bad year, an entire blend could burst.

The fix was a measurement

The solution, when it came, was measurement. If the danger came from not knowing how much sugar was in the wine, the answer was to find out and dose accordingly.

The man usually credited with it was André François, a pharmacist from Châlons-sur-Marne, in the heart of Champagne, whose treatise on the making of sparkling wines appeared in 1837.³ François worked out a practical way to measure the sugar already present in a wine and to calculate the exact additional dose needed to reach a chosen, safe level of pressure — something in the region of the six atmospheres a modern bottle carries, rather than the runaway pressure that shattered the glass. His method, known as the François reduction, gave cellar masters for the first time a reliable number to work to instead of guesswork.³

The effect was gradual but real. Through the middle of the century, breakage rates that had run to a fifth of a cellar or worse fell, with some spectacular exceptions, to somewhere between about three and eight per cent.³ That was still a real loss, but it was a survivable one, and it made the breakage predictable enough for a house to plan around. Decades later the great houses were still citing the François reduction as the cellar master’s guide.

Why it took so long

The industry lived with this destruction for as long as it did because the science that would fix it did not yet exist. Understanding fermentation as the work of living yeast, and having the chemical tools to measure sugar in a liquid, were nineteenth-century developments; before them, sparkling wine was made by feel and tradition, and the pressure it generated was genuinely unpredictable.²

The stronger, coal-fired English glass bottle had already helped by giving the wine a sturdier container to build pressure in, and better corks and wiring helped hold the pressure once it was there. But none of that addressed the root of la casse, which was the pressure itself. The bottle could only be made so strong; the real answer was to stop asking it to hold more than it could, which is what measuring the sugar allowed.

A hazard measured away

Champagne is associated with elegance now, and the dangerous decades behind it are largely forgotten. For much of the nineteenth century, though, making the wine meant working among bottles that could explode without warning, and the iron-wire masks in the old cellars were ordinary safety equipment. What ended that was a way of measuring the wine: once cellars could calculate the sugar and control the pressure, the great breakages fell to a level a business could absorb.

Related dates

The wine in your glass is often the end of a long fight with physics and chemistry. Explore what else happened on this article’s date below.

Read more

The bubbles have a long and contested history: read about the discovery of sparkling wine and the myths around Dom Pérignon, and see how the region’s story ran on into the twentieth century with the Champagne riots.

References

1. On the hazard of exploding champagne bottles (la casse) in the nineteenth century, chain-reaction breakages, losses of roughly 10–20% of a cellar in the 1840s with occasional destruction of an entire blend, and cellar workers wearing iron-wire mesh masks and gloves: Union des Maisons de Champagne and histories of champagne production. ↩
2. On the second fermentation in bottle that produces champagne’s pressure of roughly six atmospheres, its dependence on the sugar sealed in with the wine, and the nineteenth-century advances in understanding fermentation and measuring sugar: standard accounts of sparkling-wine production. ↩
3. On the pharmacist André François of Châlons-sur-Marne, his 1837 treatise on making sparkling wines, the “François reduction” for measuring sugar and calculating the dose for a controlled pressure, the subsequent fall in breakage rates to about 3–8%, and the method’s long use by the champagne houses: Union des Maisons de Champagne. ↩

Books worth reading

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Champagne: How the World’s Most Glamorous Wine Triumphed Over War and Hard Times
Don & Petie Kladstrup
A lively history of the region and its wine, danger, glamour and all.

Proof: The Science of Booze
Adam Rogers
On the chemistry and physics of fermentation — including the pressures that make sparkling wine possible.

The Story of Wine
Hugh Johnson
The sweeping global history that sets champagne’s rise in its wider context.