I designed the lights for Pajama Game. We used flash paper for the sewing machine break down. Flash paper almost immediately extinguishes itself, but we had someone assigned to a fire extinguisher backstage for that scene each time during tech and performances.
Fun fact: Parents – with construction backgrounds – built the set that year. That factory was essentially a 'house' on stage, there was no budging it. So, we just left it there all year. We used it for the house in Sound of Music in the spring, and at the end of the year an outside vaudeville group rented the theatre and used is as a brothel! The next year, and each year thereafter, we required all parent volunteers to attend a set building class!