Centuries-Old Tradition: White Smoke Signals New Pope at Vatican's Papal Conclave

On May 7, 2025, the Catholic Church's papal conclave began, drawing thousands to St. Peter’s Square to watch for white smoke from the Sistine Chapel, signaling a new pope's election. This tradition, originating in the 15th century to prevent vote tampering, evolved into a symbol of papal succession. White smoke was first used in 1914 to indicate a successful election. The smoke is produced by burning ballots and chemicals in stoves, ensuring clear signals. The conclave's secrecy contrasts with the global broadcast of the smoke, marking the election of a new spiritual leader.

Origins in the 15th Century: Secrecy and Symbolism

The term “conclave” itself originates from the Latin phrase “cum clave,” meaning “with a key,” referring to the practice of locking cardinals in a room until a new pope is elected. This tradition was formalized in 1274 at the Second Council of Lyons by Pope Gregory X through the decree Ubi Periculum, which mandated strict isolation and secrecy during the election process. The goal was to prevent external influence and ensure a swift decision.

By the 15th century, the practice of burning ballots after each round of voting had become standard. Initially, this was a security measure to prevent tampering or the leaking of information. Over time, the smoke produced from these burnings began to serve a secondary purpose: communicating the outcome of the vote to the outside world. However, for centuries, the smoke was not color-coded and simply indicated that a vote had taken place.

The First White Smoke: 1914

The turning point came in 1914 during the conclave that elected Pope Benedict XV. For the first time, white smoke was deliberately used to signal a successful election. This innovation provided a clear and immediate visual cue to the public, distinguishing a conclusive vote from an inconclusive one, which continued to be marked by black smoke.

Prior to this, other methods had been used to announce a new pope. For example, during the 1823 conclave held at the Quirinale Palace, guards fired blank rounds to signal the election. But the use of smoke—visible from afar and deeply symbolic—proved to be the most effective and enduring method.

The Mechanics of the Smoke: Stoves and Chemistry

The smoke seen rising from the Sistine Chapel is produced by burning the cardinals’ paper ballots in a cast-iron stove. This stove, first used in the 1939 conclave, is about one meter tall and bears engravings of the dates of past conclaves. Since 2005, a second stove has been added to the system, connected to the same chimney. This newer stove is used specifically to burn chemical compounds that ensure the smoke is clearly black or white.

The black smoke, or fumata nera, is created using a mixture of potassium perchlorate, anthracene (a coal tar derivative), and sulfur. This combination produces a dense, dark plume that signals no pope has been elected. In contrast, the white smoke, or fumata bianca, is generated using potassium chlorate, lactose, and pine rosin. These chemicals produce a lighter, unmistakably white smoke that heralds the election of a new pontiff.

This dual-stove system was introduced to eliminate confusion caused by ambiguous smoke colors. In the 1958 conclave, for instance, damp straw used to darken the smoke failed to ignite properly, causing white smoke to appear prematurely and misleading the crowd. Since then, the Vatican has refined the process, even stationing a technician near the Sistine Chapel to monitor the stoves and intervene if necessary.

Ritual and Timing

The conclave follows a strict schedule. Each day can include up to four rounds of voting—two in the morning and two in the afternoon. After every two rounds, the ballots are burned, and smoke is released. If no candidate receives the required two-thirds majority, black smoke is emitted. If a pope is elected, white smoke rises, followed by the ringing of the bells of St. Peter’s Basilica, a practice introduced in 2005 to further clarify the outcome.

The timing of the smoke is not fixed, but observers can often anticipate it based on the conclave’s rhythm. On the first day, only one round of voting typically occurs, with smoke expected in the early evening. In subsequent days, smoke may appear mid-morning and mid-afternoon, depending on the voting schedule.

A Global Signal

Though the conclave is conducted in strict secrecy, the smoke provides a rare and powerful moment of public participation. As the white plume curls into the Roman sky, it is broadcast live around the world, instantly informing billions of Catholics and non-Catholics alike that a new spiritual leader has been chosen.

The symbolism of the smoke—black for indecision, white for unity—transcends language and culture. It is a visual shorthand for one of the most ancient and enduring electoral processes still in use today. And while the technology behind the smoke has evolved, the core message remains unchanged: the Church has a new shepherd.

References

• Black smoke vs. white smoke: What does each mean during the papal conclave?
• The story behind ‘habemus papam’ and the white smoke announcing a new pope
• The election of a new pope is announced with smoke: what do the colours mean, and how are they made?
• When will the 2025 conclave bring a new pope? Here's how long it's taken to see white smoke in the past
• White smoke: signalling a new pope down the ages
• White smoke: signalling a new pope down the ages
• What time will we see white or black smoke from the conclave?