What Makes Flames Blue?
If you just want to produce blue flames in a campfire, throwing a little copper (II) chloride (also called cupric chloride) into the coals will do it. Copper oxychloride works too. Plain copper metal generally gives greenish flames, but having a little chlorine present gives blue. You don’t want sodium compounds. They give yellow, and will wash out the blue. Also, these things are best done outdoors (use in a fireplace will void the warranty for some types of fireplace inserts and chimneys). These materials can be purchased (by adults, anyway) at the link below, and others like it. Note that copper (II) chloride is also listed as “Campfire Blue”.
