Blacksmith coal is a specific type of coal, primarily bituminous coal, chosen for its unique properties that make it ideal for forge work. It's a fundamental fuel that allows blacksmiths to achieve the intense, localized heat necessary to shape metal.
The Preferred Choice: Bituminous Coal
For blacksmiths, bituminous is the coal-of-choice. This type of coal is a soft, mid-grade, black coal. Mined from deeper mines than lower-grade coals like lignite, bituminous coal burns much more cleanly and efficiently, making it superior for forge applications. Its ability to form a cohesive "coke" around the workpiece is crucial for concentrating heat and reducing unwanted oxidation.
Key Characteristics of Ideal Blacksmith Coal
The effectiveness of blacksmith coal hinges on several critical characteristics:
- High Heat Output (BTU): Good blacksmith coal, like bituminous, offers a high British Thermal Unit (BTU) content, ensuring it can reach and sustain the high temperatures required to make steel and iron malleable.
- Low Sulfur Content: Low sulfur is vital because sulfur can be absorbed by hot metal, leading to a condition known as "hot short," which makes the metal brittle and prone to cracking during forging.
- Low Ash Content: Less ash means less cleanup and fewer impurities interfering with the fire's efficiency and the workpiece.
- Coking Properties: The ability to "coke" is paramount. When heated in the forge, bituminous coal transforms into a porous, high-carbon fuel called coke, which burns very hot and clean. This coke forms a protective envelope around the workpiece, isolating it from direct oxygen and concentrating the heat.
- Consistency: A consistent size and quality of coal help maintain a stable and predictable fire.
How it's Used in the Forge
Blacksmiths employ specific techniques when using coal in the forge to maximize its efficiency and control the heat:
- Starting the Fire: A small amount of kindling and a starter fuel (like charcoal) is often used to establish an initial fire bed.
- Building the Coke Mound: As the fire grows, fresh bituminous coal is added to the sides of the hot zone. The heat from the established fire drives off volatile gases from this fresh coal, gradually converting it into coke.
- The "Stock Pile" Technique: When burning coal in the forge, blacksmiths often keep a “stock pile” of wet coal on the sides of the fire. This serves multiple purposes:
- Coking: The moisture helps create a low-oxygen environment, encouraging the coal to "coke" more effectively rather than burning directly.
- Containment: The wet coal acts as a barrier, shaping the fire and containing the heat within the working area.
- Fueling: As the fire consumes the inner coke, the outer wet coal dries out and turns into new coke, continuously replenishing the fuel supply.
- Controlling Airflow: An air blower (bellows or electric fan) is used to supply oxygen to the heart of the fire, allowing the blacksmith to precisely control the heat intensity.
Why Blacksmiths Choose Bituminous
The selection of bituminous coal isn't arbitrary; it's based on practical advantages:
- Localized, Intense Heat: The coking process creates a very hot, concentrated fire, allowing blacksmiths to heat specific sections of metal quickly without overheating the entire piece.
- Clean Burning (when coked): While initially smoky, once bituminous coal has coked, it burns very cleanly, producing less smoke and more consistent heat than lower-grade coals.
- Workability: The consistent and controllable heat provided by good blacksmith coal ensures the metal reaches the correct temperature for forging, preventing cracking or damage.
Other Coal Types and Considerations
While bituminous is the standard, other coal types are sometimes encountered, though they are generally less suitable:
| Coal Type | Suitability for Blacksmithing | Key Characteristics |
|---|---|---|
| Bituminous | Excellent (Coal-of-choice) | Soft, mid-grade, black. Burns cleanly, high heat, forms good coke. Mined from deeper mines. Ideal for forge work. |
| Anthracite | Fair (Difficult to use) | Hardest coal, very high carbon content. Burns very hot and clean, but is difficult to ignite and maintain due to low volatile content. |
| Lignite | Poor (Not recommended) | Softest, lowest grade. High moisture and volatile content, low heat output, produces excessive smoke, and poor coking properties. |
For those looking to source blacksmith coal, reputable suppliers specializing in forge fuels are the best option, often found through local blacksmithing guilds or online forums such as blacksmithing forums.
