Palo verde trees grow across the southwestern United States and are widely grown in landscaping for their feathery foliage. Due to their fragile nature, palo verde trees often fall in strong wind and many homeowners are left with surplus wood. While palo verde wood can be burned outdoors with few problems, it possesses several traits that make it undesirable for use in an indoor fireplace.
Palo verde wood has a porous structure with a weak central core, so it cannot sustain heat for a long period of time. The speed with which it burns makes it less useful as firewood since it provides heat for a limited time and requires frequent replenishing. While it can be used successfully as kindling since it catches fire quickly, there are other factors that make palo verde wood unsuitable for indoor use.
Fresh palo verde wood emits a subtly fruity scent that turns sour and unpleasant when the wood is burned. The odor of burning palo verde wood has a lingering quality that is difficult to remove from fabric and can persist for days in an enclosed environment. In addition, the pungency of the smell induces headaches and allergies in many people, so it should be avoided in an indoor environment.
Lack of Coal Formation
Coal formation is the result of pyrolysis, or thermal decomposition. It occurs during a sustained period of burning during which the intense heat surrounding the fuel robs the surrounding air of oxygen, causing the wood to break down into carbon. Most firewood undergoes pyrolysis to produce the glowing coals characteristic of a successful fire. However, palo verde wood cannot produce coals due to its porous structure and light weight, which burns too rapidly to successfully undergo pyrolysis. A lack of coals means that a fire comprised of palo verde wood will not produce adequate heat and is therefore of little use within an indoor fireplace.
A crackling sound is normal when wood burns, but palo verde wood pops and crackles more than most. The sound is produced as the interior of the wood heats and the hot air is expelled through the outer layer of the wood. Palo verde wood possesses a very weak structure, so the natural popping noise is often accompanied by a burst of embers as the wood splinters. In an indoor fireplace, the expelled embers pose a safety hazard since they can easily land on flammable surfaces such as carpets or furniture and cause a fire.