What makes the white smoke that announces a new pope?

White smoke appears above the Sistine Chapel when cardinals burn a special chemical mixture—primarily potassium chlorate, lactose, and rosin—in a dedicated stove, signaling that a new pope has been elected and has accepted. Black smoke, produced by a different mixture, indicates no decision; church bells now accompany the white smoke to avoid confusion.

How the signal works today

Since the mid-2000s, the Vatican has used a two-stove system inside the Sistine Chapel to make the “fumata” unmistakable. One stove burns the paper ballots; a second, purpose-built stove burns chemical cartridges that produce either white or black smoke. Both stoves vent through a single flue to the chapel roof, where the plume is visible to crowds in St. Peter’s Square and to worldwide broadcasts. When the smoke is white, the bells of St. Peter’s Basilica also ring, reinforcing the message that a pope has been chosen.

The chemistry behind the colors

The color of the smoke is no longer left to chance or the dampness of straw, as in earlier centuries. Instead, Vatican technicians use defined chemical mixtures that produce dense, unmistakable plumes.

The following list outlines the typical compositions used to create the contrasting signals.

• White smoke (fumata bianca): a mixture commonly including potassium chlorate, lactose (milk sugar), and rosin (colophony) to generate a thick white plume.
• Black smoke (fumata nera): a mixture commonly including potassium perchlorate, sulfur, and anthracene to yield a dark, sooty signal indicating no successful ballot.

Together, these mixtures ensure that observers clearly distinguish a successful election from an inconclusive vote, addressing past ambiguities caused by simple paper or straw burns.

The procedure inside the conclave

When a ballot concludes, cardinals deposit their papers into the main stove to be burned. If no candidate reaches the required threshold, technicians ignite the “black smoke” compound in the auxiliary stove. If a two‑thirds majority is reached and the chosen cardinal accepts, the “white smoke” compound is ignited, producing a bright plume visible for several minutes. The appearance of white smoke is quickly followed by the ringing of the basilica’s bells and, later, the traditional Habemus Papam announcement from the balcony.

Why the system was updated

Historically, the Vatican used damp straw to darken the smoke after unsuccessful ballots and dry materials to lighten it, which sometimes led to confusion—especially in poor weather or fading light. To prevent misinterpretation, the Vatican introduced the modern chemical system and a second stove in the 2005 conclave and used it again in 2013. The bell-ringing protocol was formalized alongside, making the signal redundant and unmistakable.

Common misconceptions

It’s a common belief that the ballots alone produce the white smoke. In fact, while the ballots are always burned, the vivid white or black plumes that the world watches for are produced by controlled chemical mixtures burned in a separate device. The smoke’s color is not about the paper’s condition but about the compounds designed to signal the result.

What happens when a pope is elected

The process from a successful vote to the public signal follows a carefully choreographed sequence inside the sealed conclave and the Vatican precincts.

1. Cardinals reach a two‑thirds majority for one candidate in a secret ballot.
2. The dean (or a senior cardinal) asks the chosen cardinal if he accepts; upon acceptance, he selects a papal name.
3. Ballots are burned in the main stove while the auxiliary stove produces white smoke using the dedicated chemical mixture.
4. The bells of St. Peter’s Basilica ring to confirm the white smoke signal to the crowd and global audiences.
5. After preparations and vesting, the senior cardinal deacon appears on the central balcony and proclaims Habemus Papam, introducing the new pope by his chosen name.

This sequence ensures that the visual cue (smoke) and the auditory cue (bells) precede the formal proclamation, giving the world both an immediate sign and an official announcement.

History and tradition

Smoke signaling at papal conclaves dates back to the 19th century, gaining prominence in the 20th. Earlier conclaves relied on burning ballots with straw to produce lighter or darker smoke, but weather and lighting often muddied the message—most notably in the 20th century, when grayish plumes sparked speculation. The introduction of precise chemical mixtures and bell-ringing has preserved the beloved tradition while eliminating ambiguity, allowing the global audience to recognize a new pontiff at a glance.

What people see and hear in St. Peter’s Square

For those gathered in the square or watching live feeds, the crucial cues are straightforward: a sustained white plume curling from the chapel’s chimney, followed by jubilant bell peals. After an interval for internal protocols, the new pope steps onto the central loggia to give his first blessing, Urbi et Orbi, marking the formal start of his pontificate.

Summary

White smoke signals a new pope because Vatican technicians ignite a specific white-producing chemical mixture—typically potassium chlorate, lactose, and rosin—in an auxiliary stove connected to the Sistine Chapel flue. Black smoke, from a different mix, indicates no result. Since the mid-2000s, this system, paired with the ringing of St. Peter’s bells, has made the ancient fumata tradition clear and unmistakable to the world.

What chemical is used to make the smoke white at the Vatican?

“The black smoke was produced by a mixture of potassium perchlorate, sulfur and anthracene, a chemical found in coal tar. The white smoke on the other hand was derived from a mixture of potassium chlorate, lactose, and some pine resin known as Greek pitch,” Canada’s McGill University detailed in a 2017 explainer.

What makes the smoke white pope?

White inside the chapel. There are two stoves. One that burns the cardinals votes after they have been counted. And another connected to it which handles the pyrochnic.

What was the white smoke at the pope election?

The white smoke and the “Room of Tears”
After the rite of acceptance is completed, all the ballots and other election-related documents are burned, and the resulting white smoke signals to the world that a new Pope has been chosen.

What does the white smoke mean in the Catholic Church?

White smoke from the chimney on top of the Sistine Chapel (Vatican City) indicates that the Pope has been elected.