As black smoke poured from the Sistine Chapel’s chimney this morning, indicating that despite three ballots the cardinals have failed to elect the new pope, the Vatican released the pyrotechnical formula for the “mystery” recipe used to produce the holy puffs.

“It’s no secret,” Father Federico Lombardi, the Vatican spokesman, said at a news conference today.

The process involves the use of two stoves. One, first employed in 1939 to elect Pope Pius XII, is used to burn the ballots. Another, more modern stove was introduced in 2005 to augment smoke and send a clear signal out to St. Peter’s square. Copper stovepipes protruding from the top of each stove are joined into a single pipe which runs up out of the window to the chimney.

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“As the ballots are burned in the old stove, an electronic device is activated in the more modern one which puts into action a cartridge. This is  filled with five doses, released every minute, to produce the colored smoke,” Lombardi said.

Black smoke, indicating no pope, is created with mixture of potassium perchlorate, anthracene (a component of coal tar), and sulfur.

White smoke, which announces the election of a new pope, is made with a combination of potassium chlorate, milk, sugar and pine rosin.

The tradition to use the smoke signals dates back to less than 150 years. It started with il Risorgimento, the military unification of Italy, when an offended Pope Leo XII decided to give his papal address inside the Vatican rather than on the balcony of St. Peter’s.

“They felt they were prisoners of Italy and didn’t want to recognize the violence suffered. But they had to tell the world it had a new pope so they invented this system of lighting a fire and letting the smoke speak,” Ambrogio Piazzoni, the director of the Vatican’s Apostolic Library,  was quoted as saying in a post by the St Michael Society.

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Later on, Pope Pius X (1835 – 1914) established that once the votes had been counted they had to be burned to maintain secrecy. The white smoke first appeared at Pius X’s death in 1914 with the election of Pope Benedict XV.  On that occasion, the cardinals set up the white/black smoke color rule.

To produce a darker smoke, and announce the inconclusive election,  wet straw was used. But the problem of distinguishing the smoke color remained, and confusion reigned in St. Peter’s Square.

It was Pope John Paul II that added the rule of bells ringing after the appearance of white smoke, to make it clear that a pope was elected.

Father Lombardi reassured that in the two burning sessions no smoke entered the Sistine Chapel.

“Michelangelo’s frescoes are safe,” he smiled.

Indeed, a resistance wire is used to preheat the copper stovepipe so it draws correctly. Inside the pipe, a fan is used to further ensure that the smoke doesn’t spread into the chapel.

Photo: Rossella Lorenzi