During the 2013 conclave that led to the election of Pope Francis, the black smoke was produced using a mixture of potassium perchlorate, anthracene (a component of coal tar) and sulfur.

Black smoke emerging from the chimney means the world's 1.4 billion Catholics don't yet have a new pope. White smoke means the cardinals have chosen a new leader of the church.

Here's what to know about the black and white smoke used during a papal conclave. Start the day smarter. Get all the news you need in your inbox each morning.

Black smoke indicates a non-conclusive answer, and white smoke indicates that a new pope has been selected. Here's what to know about the black and white smoke used during a papal conclave.

It wasn’t clear whether grey smoke was closer to black or white, for example. By the 1970s, the straw method had been abandoned in favour of more controllable chemical mixtures.

Black smoke indicates a non-conclusive answer, and white smoke indicates that a new pope has been selected. This process is part of a papal conclave.