The Sulphur Revolution

by Charlie Leary

In 1809, the New Complete Course of Theoretical and Practical Agriculture by Philibert Monet (Nouveau cours complet d’agriculture théorique et pratique) noted that everything connected to the art of preserving wines, “we can reduce to sulphuring and clarification”.

Indeed, French wine historians attribute to the sulphur “match” a key role in the quality revolution of the early 18th century, which produced the grands crus of Bordeaux. Far from being a minor technical innovation, introducing sulphur matches into Bordeaux winemaking fundamentally transformed the region’s wines. By controlling fermentation, preventing the formation of vinegar, and enhancing colour, sulphur allowed Bordeaux wines to develop ageability and complexity. This simple practice laid the foundation for the reputation of Bordeaux wines as exceptional, long-lived, and valuable.

Adding sulphur to wines, both red and white, has a long history that started outside Bordeaux. The practice originated longer ago than many believe. Some attribute the use of the romantic-sounding allumette hollandaise, or Dutch match, to the 18th century, but burning the mèche de soufre in winemaking has a more intriguing history.

Although many today decry the use of sulphur dioxide in winemaking, the so-called mèche contributed hugely to enhancing the quality and hence the ageability of Bordeaux wines, which made them particularly valuable. In the early 17th century, most wine would turn sour within six to ten months. There was no thought of ageing, tertiary aromas, or shelf-life. The mèche helped change that.

How and when did this happen? How did the sulphur get into the wine? Was this considered adulteration?

Early History
Already in 1600 the Frenchman Olivier de Serres, just after discussing flavouring wines, including “Vins clerets et rouges,” noted that the Germans used sulphur to “parfumer les tonneaux” (tonneaux were very large wooden wine barrels, holding almost 1,000 litres).

He wrote: “On a brazier, they burn sulfur, the smoke of which is led into the barrels through a funnel placed in the bung hole.” [see the main image above] He added: “Once the wine is barrelled, it keeps for a long time in good condition.” This was a foreign practice for Serres and still in a rudimentary state, if you can imagine being in the same room with a hot brazier filled with sulphur. The burning process created sulphur dioxide, SO2, which could dissolve into the wine. By 1635, the “mesche de soufre” was listed in a French-Latin dictionary.

By the mid 17th century, Dutch traders were arriving in Bordeaux. They became, for a while, the international leaders in wine commerce. They adopted the sulphuring of barrels at the same time. Their initial purpose, however, was to stop fermentation of white wines so that they would remain sweet. The SO2 killed the yeast that consumed the sugars in the wine, converting them into increasingly more alcohol and CO2. The liquid resulting from the stopped fermentation became known as “stomme”.

A sweet wine style suited Dutch market demand, but the Dutch government viewed too much SO2 in stomme as having negative health consequences. Hence, its importation was outlawed in 1613. The prohibition was totally ineffective, however. According to the historians Mariëlla Beukers and Rob Blijleven, stomme from Bordeaux, called hooglandsche stomme, commonly traded in Amsterdam until the late 1750s.

Sulphuring suited Dutch economic interests in shipping Bordeaux wine across long distances. They, too, came up with the “match” or mèche,  which wasn’t exactly like what you find in a box of matches. The “match” was actually linen or cotton cloth coated with liquid sulphur and sometimes aromatic ingredients (to disguise the SO2 aroma in the wine). The cloth was lit on fire and then shoved into the barrel—no more brazier. The sulphur coated the walls of the barrel and then dissolved into the wine upon contact. A second method included burning the “match” over a barrel partly filled with wine. Both involved an iron wire that supported the impregnated cloth during combustion.

Stomme and Vin Muet
It’s important differentiate stum or stomme from the finished white wine. Stomme was an extremely dense, sticky liquid must resulting from stopped fermentation. It had  high levels of sulphur dioxide and sugar. A technique of creating a highly sulphurous concentrated stomme and then adding additional young wine to it was a technique specific to Bordeaux. The result was a sweet, low-alcohol white, called vin muet. You could think of it like the ancient version of sweet Moscato today. It was extremely important to Bordeaux’s “bulk wine” economy in the 17th and early 18th centuries.

A 1730 document from Blaye explained how le vin muet was made using white wine must. “One starts with 1/3 in a barrel which is then sulphured heavily.” This was the stomme. After extensive stirring, “the same quantity of must wine is poured into the barrel,” followed by more stirring but no additional sulphur. After the final 1/3 was added, “one pours it into another barrel” for sale. “Wine, prepared in this way, does not continue to ferment and keeps its freshness and taste,” the author noted.

Sulphuring Spreads
By 1659, English traveller Lohn Lauder reported that all French wine intended for export had added sulphur. This was not all vin muet, however. Lauder, of course, referred to it using the English word brimstone, as in “fire and brimstone.”

While the initial purpose of creating SO2 was to halt fermentation, it had other effects, particularly two that became important in relation to the evolution of dry Bordeaux red wines. Firstly, it killed the bacteria that produced vinegar, which caused wine inevitably to turn horribly sour within a few months, and secondly it helped prevent browning and intensified the red wine’s colour.

William Hughes’ book, The Compleat Vineyard, of 1665 supports Lauder’s observation. He advocated a technique for adding brimstone to wine but also emphasized the importance of bottling it as soon as possible to prevent deterioration from air contact. He also described Haut-Brion as a dark red wine in 1670.

In a humorous tone, Hughes advised that “when you find” your wine “begin to grow flat never so little, you may dip a piece of linen cloth in melted brimstone, and put it in at the Bunghole of the cask, and set it on fire, the linen cloth and brimstone I mean, (not the cask) and let it so hang in the cask by some wyer or some such like thing till it be burnt, keeping in the sulpherous vapours as much as you can, and so stop it up close again, this doth help-decaying Wine very much, by adding spirits thereto, for all Wines have in them a Sulpherous part as may be proved and seen in burning.”

Wine that Can Age
If Bordeaux wines, not only the grands crus but also the coarser wines sent across the oceans to growing colonial empires, had one singular characteristic in the 18^th century, it was shelf life. Ageing allowed such wines to soften, open up, and express new flavours. Would that have been possible without the mèches de soufre? Not likely.

In 1781, Samuel Ricard’s Traité général du commerce advised that Bordeaux wine merchants regularly used “un meche de deux pouces” plus isinglass to prepare white wines, but for reds, during racking in May, “one must burn un pouce de meche de soufre” in the new barrel and then stir the wine with egg whites (a dozen eggs per barrel). As the New Complete Course reiterated in 1808, sulphuring and clarification went hand-in-hand. But, notably, reds received half the amount of SO2 as white wines. Even so, in part thanks to higher levels of dissolved phenolic compounds, these wines could stay in the warehouses of Chartrons merchants for years, improving and becoming more valuable.

In all, by the 1660s, the German technique of sulphured barrels had evolved via Bordeaux’s Dutch community into creating stomme and vin muet; and it was increasingly applied to red wines. This coincided with the creation of darker, more highly phenolic red wines in Graves and then Medoc. In turn, once vinegar-producing bacteria were killed by the sulphur, the wines could age over a period of years – so helping create the modern Bordeaux red wine style of a wine that could be laid down and would improve over ageing. A small technique with a huge impact.