“The explosion almost killed both of them. This butane hash oil is nothing to play with.” Marijuana smokers have been making hash oil using solvents such as butane or ethyl alcohol since the 1960s.

Dear Gene: You’re allowed to make concentrates that don’t require butane, like bubble hash, kief, QWISO hash from rubbing alcohol, and other concentrates extracted with water. As I’m sure you know, ...