Locust wood is highly regarded for use as firewood, standing out among hardwoods for its exceptional heating properties. Primarily, the species known as Black Locust is the one sought after by those who heat their homes with wood. Its unusual density and high energy content make it a superior choice for sustained heat production.
The Exceptional Heat Output of Locust Wood
The reputation of locust wood stems from its remarkable density, which is directly linked to its heat output. A cord of seasoned Black Locust weighs over 4,000 pounds, a figure that is significantly higher than many other hardwoods and nearly double the weight of a softwood like white pine. This high specific gravity means that a greater amount of burnable material is contained within a given volume of wood.
This density translates into an outstanding British Thermal Unit (BTU) rating, often cited around 26.8 million BTUs per cord, positioning it near the top of all available firewoods. The high BTU rating ensures the wood burns very hot, making it ideal for heating large spaces or maintaining warmth during deep cold. The density also contributes to a long, slow, and steady burn time, which is particularly valued for overnight heating. Locust wood breaks down into a deep bed of coals that retain heat for an extended period, allowing a fire to be easily rekindled the following morning. Furthermore, because the wood burns so thoroughly, it leaves behind a relatively minimal amount of fine ash, reducing the frequency of stove or fireplace cleaning.
Essential Preparation and Seasoning Requirements
Preparing locust wood for burning involves managing its physical properties, particularly its hardness and grain structure. Black Locust is known for having a tough, often twisted grain that resists splitting once the wood has dried out. This characteristic makes it highly advisable to split the logs shortly after the tree has been felled, while the wood is still in a green state.
The wood’s initial moisture content is relatively low for a hardwood, often around 27 percent when green. Despite its density, Black Locust seasons faster than many comparable hardwoods, such as oak. Under ideal conditions, including splitting and stacking in a sunny, breezy location, Black Locust can reach the target moisture content of 20% or less within six to twelve months. Seasoning for a full year is generally recommended for optimal performance, ensuring maximum BTU output and a clean burn. Utilizing a moisture meter is the most reliable way to confirm the wood is ready for combustion. Burning wood with a moisture content above 20% reduces the heat output, as energy is wasted boiling off the excess water.
Distinguishing Between Locust Species
When discussing locust firewood, it is important to differentiate between the two main species: Black Locust (Robinia pseudoacacia) and Honey Locust (Gleditsia triacanthos). Black Locust is the superior firewood, known for its extreme density and high heat. Its heartwood typically displays a distinct yellow or greenish-yellow color.
Honey Locust is also a dense hardwood and an excellent fuel source, but it is generally considered slightly less dense than its black counterpart. The thorn patterns are a key physical difference: Black Locust often has smaller thorns on the branches, while Honey Locust can feature massive, branching thorns on its trunk and limbs (though thornless varieties exist).
Handling and Safety Considerations
The combustion properties of Black Locust necessitate certain safety precautions during handling and burning. This wood is prone to sparking and popping as it burns, a result of its intense heat and internal structure. For this reason, always using a sturdy fireplace screen or keeping the door of a wood stove closed is a necessary safety measure when burning locust indoors.
The wood burns exceptionally hot, which can lead to a rapid accumulation of creosote if the fire is consistently dampened or choked. Regular chimney cleaning is particularly important when using this wood to mitigate the risk of a chimney fire caused by excessive creosote buildup.
Handling the wood requires caution, especially with thorny varieties, as the sharp thorns can cause injury. Wearing thick gloves during the processing and stacking stages is a simple action to prevent accidental punctures. The high heat output also means stove operators must carefully manage the air supply to avoid over-firing a wood stove, which could potentially cause damage to the appliance.