How Vatican produces black, white smoke
VATICAN CITY – The famous smoke from a chimney to indicate whether cardinals locked away in the Sistine Chapel have elected a pope is not created just by burning used ballots, the Vatican said Tuesday, March 12.
"We use smoke flares," Paolo Sagretti, who was in charge of setting up the chapel for the election conclave, told AFP.
The ancient signalling system – still the only way the public learns whether a pope has been elected – used to involve mixing wet straw with the ballots to produce white smoke, and pitch to create black smoke.
After several episodes in which greyish smoke that could be interpreted as white or black created confusion, the Vatican introduced the surer system starting with the last conclave in 2005.
The Vatican now uses a mixture of potassium perchlorate, anthracene, and sulphur to produce black smoke and potassium chlorate, lactose, and rosin for white, the Vatican says on its website.
Two stoves stand in a corner of the chapel, one for burning the ballots and the other for the chemicals, with the smoke from both stoves going up a common flue.
An electronic control panel allows the choice between the two, and the correct compound is burned at the same time as the used ballots. – Rappler.com