Varying chemical compounds have replaced wet straw and pitch to produce the Vatican smoke signal that is used to communicate the result of conclave voting sessions.
Fr. Thomas Rosica, assistant to the Vatican press office director, explained that since 2005 the Vatican has used chemical compounds to better communicate the result of the conclave.
“For a Church that has made much progress in the area of modern communications, computer technology, Internet and Twitter, the conclave still relies on smoke signals to let the world know of its results,” he said in a March 11 statement to the press.
In the past, wet straw was used to create the white smoke, while pitch – a tar-like substance – was used to create black smoke.
Due to a number of “false alarms” in the past, Fr. Rosica explained, the Vatican has sought the help of “modern chemistry” to produce more easily distinguishable shades of smoke.
Now, the black smoke is produced by a mixture of potassium perchlorate, anthracene, and sulphur, while the white smoke is made by burning a mixture of potassium chlorate, lactose, and rosin – a natural amber resin.
A traditional stove inside the Sistine Chapel is used to burn the ballots following a voting session, while a separate stove that sits alongside it helps produce the distinctive black or white smoke.
Depending on the result of the vote, an electronic control panel is used to request chemical compounds that have been pre-mixed by Vatican technicians which will then produce either shade of smoke.
Although two separate units are used to create the smoke, the plume comes out of one chimney by the time it emerges above the Sistine Chapel. The smoke stack is pre-heated and contains a backup fan to help ventilation if necessary.
Black smoke, as was seen at 7:42 p.m. Rome time March 12, indicates a failed conclave. By contrast, white smoke accompanied by the ringing of the Vatican bells will signal that a new Pope has been selected.