Following the death of Pope Francis on Easter Monday, the conclave is set to commence today (May 7) to begin the papal selection process and choose a new leader of the global Church.
The famously secretive process will see 133 senior members of the Catholic clergy, Cardinals, gather to elect Pope Francis’ successor.
Inside the Sistine Chapel, the doors are locked and the room is swept for recording devices in preparation for the secret voting process to begin. While the cardinals gather, the world watches for smoke to rise from the chimney as it signals whether or not a new Pope has been chosen.
Black smoke indicates an unsuccessful vote with no pope appointed. White smoke means Habemus Papam: We have a pope.
Read also: Who could be the next Pope after Francis? All the cardinals in the running for the Papacy
How does the Vatican make white smoke?
The smoke is created by burning the ballot papers in a stove inside the chapel. To colour it according to the outcome, this burning is mixed with chemicals inside a second stove.
For black smoke, the Vatican uses a mixture of potassium perchlorate, anthracene, and sulphur. The white smoke used to signal that a Pope has been chosen is created from potassium chlorate, lactose, and a type of conifer resin called rosin.
In essence, the Vatican uses oxidisers (potassium perchlorate and chlorate) combined with carbon sources (lactose and rosin). Electrical heating of the flue and backup air fans are also deployed to make sure the smoke does not change colour and that it rises in one single stream.
However, this has not always been the method used. Before the above chemical concoction, the Vatican had a simpler formulation for controlling the colour of the smoke.
For white smoke, wet straw and damp grass was used, whilst tarry pitch, a dark and viscous substance made by distilling coal, would turn the smoke black. The problem with the latter was that it was potentially full of carcinogenic carbon particles that are harmful to humans.
Why do they rebuild the chimney each election?
The chimney was installed on the Sistine Chapel last week ahead of the conclave meeting and will be removed after the election process is complete.
As the Sistine Chapel is first and foremost a chapel, its roof has not been designed to facilitate a chimney. Nor has the Michelangelo-adorned ceiling been designed to withstand and release smoke signals.
Therefore, construction workers form a temporary hatch from which to place the flume. The flume then emerges through the tiled roof, so that it is visible to those patiently waiting outside in St Peter’s Square.
Despite the chimney being a temporary fixture, it is robust, solid, and completely safe.
Every joint is sealed to prevent leaks, with every component vigorously tested. Smoke tests also take place before the conclave to make sure everything is in order.
Vatican firefighters are also on standby throughout the process.
Read also: The fantasy football-inspired game Italians are playing to pick the next Pope
