They don’t mix. Not at all. See what happens when burnt popcorn sets off fire alarms in a library:
The building was evacuated around 2:10pm on Wednesday and reopened – amazingly – shortly after 5pm. Thankfully, there was no fire but when staff did their initial walk-through around 2:40, a major leak was discovered on the 1st floor, another on the 3rd floor. Staff kicked into high gear and quickly rolled out the disaster bins and grabbed the plastic tarp to cover shelves getting soaked. As soon as the shelves were covered, the book truck brigade began pulling materials that were wet and moved them to a staging area on 5th floor.