What might be used to make white smoke?“There are certain combustion products that are white or lighter gray based on their nature,” says Mocella. He points to certain zinc compounds and elemental phosphorus, which attract moisture when burned and can produce thick white smoke. “These are fairly straightforward reactions for a pyrotechnic chemist,” he adds.

Any idea about the Vatican’s white smoke methodology?Vaporization is definitely an option, but it’s complicated to master, Mocella says. He suspects that the cardinals use the simpler process of combustion. One easy way to create white smoke is to burn “metallic zinc dust with elemental sulfur, generating zinc sulfide gas that is a thick off-white cloud of smoke when generated.”

What about black smoke?Black smoke is best made by partially burning organic material, like wood, says Mocella. “If we limit the amount of available oxygen in a fast-burning pyrotechnic composition, we’ll get a lot of not-completely-burned sooty particles: smoke!”