A quick glance at the heating properties of Osage orange may suggest that this tree is the world’s best firewood (if you don’t mind battling thorns and sharpening chainsaw blades frequently). After all, this dense wood is the hottest-burning firewood east of the Rocky Mountains, producing as much as 32.6 million BTUs per cord according to K-State. That’s enough heat to warp a wood-burning stove without proper precautions to keep the temperature down.
But sitting in front of an Osage orange fire can be anything but restful. Once the wood heats up, the constant shower of sparks can transform your fireplace into a miniature fireworks display.
Sparking occurs when the wood releases sap, which in this species is a thick, sticky white substance containing latex. The sparking increases dramatically if the fire is suddenly exposed to air.
You can mitigate, but not completely eliminate, the spark shower by allowing the sap to dry out before burning. Osage orange dries very slowly, taking from six months to two years depending on the size of the pieces. Note that the wood should be split before drying begins. Dry Osage orange is remarkably like iron.
It’s always best to be on the safe side, even with dry wood. Never burn Osage orange in an open fireplace, and never leave the fire unattended.