VATICAN CITY — As millions prepare to watch history unfold once again from St Peter’s Square, the Vatican’s centuries-old smoke signal tradition is taking centre stage ahead of the election of a new pope.
Following the death of Pope Francis on Easter Monday at the age of 88, cardinals from around the globe will gather on 7 May inside the Sistine Chapel to begin the conclave—the secretive and sacred process of selecting the next leader of the Catholic Church.
But long before a single ballot is cast, a team of engineers, chemists, and Church officials have been hard at work setting the stage for one of the world’s most symbolic spectacles: the rising smoke that announces to the world whether a decision has been made.
“From antiquity onwards, people have seen rising smoke as a form of human communication with the divine,” said Candida Moss, theology professor at the University of Birmingham.
“In Catholic tradition, prayers ‘ascend’ to God. The use of smoke evokes these religious rituals and the aesthetics of wonder and mystery that accompany them.”
In keeping with a practice that dates back to the 15th century, the burning of cardinals’ paper ballots is not just a matter of disposal, but one of dramatic signalling. Black smoke means no consensus; white smoke—along with the phrase Habemus Papam—announces a new pontiff.
Behind the scenes, the process is meticulously planned. Two temporary stoves are installed inside the Sistine Chapel, one to incinerate ballots and the other to produce coloured smoke. Both stoves are linked to a specially constructed flue that exits through a discreet chimney atop the chapel’s roof.
The flue, typically made of metal such as iron or steel, is inserted via an existing opening or temporary hatch, with every joint sealed to prevent leaks.
“The system has to work perfectly,” explained structural engineer Kevin Farlam. “If one thing goes wrong, it’s not just a technical failure—it becomes an international incident.”
To ensure that smoke signals are clearly visible, Vatican technicians use pre-packed chemical cartridges that are electronically ignited. According to chemistry professor Mark Lorch, black smoke is produced using potassium perchlorate, anthracene, and sulfur. For white smoke, potassium chlorate, lactose, and pine rosin are used.
Earlier attempts to use damp and dry straw often caused confusion, with the smoke appearing grey and ambiguous. The modern chemical approach ensures clarity—an essential requirement in an age of instant global news.
In addition to the smoke, bell ringing—introduced during the 2005 election of Pope Benedict XVI—now serves as an auditory confirmation of a successful vote.
Despite calls over the years to replace the tradition with digital updates or televised announcements, the Vatican has stood firm.
“This is about continuity,” said Prof Moss. “It’s a ritual steeped in secrecy, symbolism, and history. For the Catholic Church, innovation is almost antithetical to ritual.”
As the conclave nears, scaffolding is up, the chimney is in place, and the world waits—not for an app notification, but for a puff of smoke against the Roman sky.