Lu Yu’s Discourse on Fire:
Of fire, use charcoal; inferiorly, use sturdy firewood ( these are called varieties of mulberry, pagoda tree, and oak. ) Of charcoal, do not use those that were once roasted, odorous and greasy ( such as that used for cooking ) ; oily woods ( containing pitch ) ; and failed utensils ( Oily woods are cypress, pine, and juniper. Failed utensils are rotten or worn-out useless wooden utensils. ) The ancients had the odor of toiled Firewood. This is believable!
Lu Yu - Tang dynasty China
Source for pic and lesson: The ancient art of Tea: Wisdom from the old Chinese tea masters